Suppression of stress corrosion cracking in high magnesium alloys through the addition of calcium

ABSTRACT

A stress corrosion cracking-resistant aluminum alloy product may include aluminum and a plurality of alloying elements. The plurality of alloying elements may include 3 wt. % to 10 wt. % magnesium and at least one of 0.001 wt. % to 0.1 wt. % calcium. In some embodiments, the plurality of alloying elements may further include 0.001 wt. % to 0.1 wt. % strontium. In some embodiments, the plurality of alloying elements may further include silver.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. ProvisionalApplication No. 62/949,286, filed on Dec. 17, 2019, which is herebyincorporated by reference in its entirety.

FIELD

The present disclosure relates to metallurgy generally and morespecifically to metal alloy products that resist stress corrosioncracking and methods of making metal alloy products.

BACKGROUND

High-strength and durable aluminum alloys are desirable for use in anumber of different applications. Magnesium in solid solution iseffective in strengthening aluminum alloys, and magnesium-containingaluminum alloys are relatively inert because magnesium oxide that formsat the surface creates a barrier to corrosion. For example, 5xxx seriesaluminum alloys are generally considered relatively inert to seawatercorrosion and thus are particularly useful in marine construction oroffshore applications. 7xxx series aluminum alloys also demonstrate goodcorrosion resistance in most environments. Nonetheless, 5xxx seriesaluminum alloys containing relatively high content of magnesium (e.g., 3wt. % or greater) as an alloying element, as well as 7xxx seriesaluminum alloys containing low or no copper and 7xxx series aluminumalloys or containing relatively high combined content of zinc,magnesium, and copper (e.g., 6 wt. % or greater), can experience stresscorrosion cracking over time.

Stress corrosion cracking usually occurs at the grain boundaries wherestress corrosion cracks may make a trans granular path, especially atthe later stages when the failure is more mechanical than corrosive. Thestart of the cracks requires an indentation in the metal, such as a deeppit or an etched grain boundary. The growth of the cracks generallystarts slow, but then transforms and becomes rapid. Roughly, about 70%to about 90% of the time to failure is for nucleation of the crack.Cracks can also be triggered when vacancies or dislocations pile up.

Tension (i.e., stress) is often a prerequisite for stress corrosion, andin bent samples, the cracking almost always starts in the tension side.The corrosion rate is generally proportional to the load, such that thehigher the load the shorter the life. In wrought products, the directionof the load in relation to the grain orientation is important. A load,applied in the short transverse direction, can be less than one-fifth ofthat for the long transverse or longitudinal direction.

The denuded zones near the grain boundary and sub boundaries can play animportant role in crack generation. Crack initiation may be tied to thedenuded zone around the grain boundary, which may remain super saturatedthe longest with the greatest electronegativity with respect to thematrix balance. The precipitates at the edge of the grain may advancethe crack (like postage stamp perforations), but the electronegativityin the denuded region may be responsible for the crack initiation.

Stress corrosion susceptibility may be related to oxide film ductilityand crack growth rate. This stress corrosion susceptibility can be aresult of the crack growth passivation rate: if the crack grows fasterthan passivation occurs, failure ensues. Corrosion without stress tendsto accelerate the eventual stress corrosion crack rate.

Structure can also be an important influence on stress corrosioncracking. Fine grain size decreases susceptibility, but a large numberof sub-boundaries may produce a much larger improvement in resistance.

Stress corrosion cracking of aluminum alloys containing magnesium caninvolve a condition where magnesium-containing precipitates at the edgeof a recrystallized grain in conditions where increased temperatureand/or time promotes the nucleation and growth of certainmagnesium-containing precipitates, such as the Mg₅Al₈ beta phaseparticles for a 5xxx aluminum alloy or the MgZn₂ eta phase particles fora 7xxx aluminum alloy, at the recrystallized grain boundary to form asemi-continuous string, similar to a string of pearls. The relativeelectronegativity of the Mg₅Al₈ beta phase or the MgZn₂ eta phase withrespect to the surrounding material in the grain creates a corrosionevent near the Mg₅Al₈ beta phase or the MgZn₂ eta phase particles.Eventually, the corrosion cells, coupled with the Mg₅Al₈ beta phase orthe MgZn₂ eta phase, forms weak areas in the microstructure that crackor tear, similar to how perforations formed between postage stamps canbe used to guide their separation.

Depending on the precipitates out of the matrix, the precipitateparticles may or may not be continuous, or may be separated orscattered. However, the crack may nonetheless propagate and compromisethe integrity and eventually cause the failure of the alloy structure.

SUMMARY

The term embodiment and like terms are intended to refer broadly to allof the subject matter of this disclosure and the claims below.Statements containing these terms should be understood not to limit thesubject matter described herein or to limit the meaning or scope of theclaims below. Embodiments of the present disclosure covered herein aredefined by the claims below, not this summary. This summary is ahigh-level overview of various aspects of the disclosure and introducessome of the concepts that are further described in the DetailedDescription section below. This summary is not intended to identify keyor essential features of the claimed subject matter, nor is it intendedto be used in isolation to determine the scope of the claimed subjectmatter. The subject matter should be understood by reference toappropriate portions of the entire specification of this disclosure, anyor all drawings and each claim.

Described herein are stress corrosion cracking-resistant aluminum alloyproducts. The aluminum alloy products described herein advantageouslyexhibit good resistance to corrosion through the inclusion of calcium,strontium, and/or silver in the alloy, which allows the aluminum alloyproducts to resist crack formation and growth and fracture while understress in corrosive environments. Stress corrosion cracking resistanceand classification of metals, such as aluminum alloys, can be determinedaccording to various standard test methods, such as ASTM G139-05(2015),Standard Test Method for Determining Stress-Corrosion CrackingResistance of Heat-Treatable Aluminum Alloy Products Using Breaking LoadMethod, ASTM International, West Conshohocken, Pa., 2015, or ASTMG64-99(2013), Standard Classification of Resistance to Stress-CorrosionCracking of Heat-Treatable Aluminum Alloys, ASTM International, WestConshohocken, Pa., 2013, ASTM G47-98(2019), Standard Test Method forDetermining Susceptibility to Stress-Corrosion Cracking of 2XXX and 7XXXAluminum Alloy Products, ASTM International, West Conshohocken, Pa.,2019, which are hereby incorporated by reference.

Advantageously, the inclusion of calcium, strontium, and/or silver inthe alloy provides a level of corrosion resistance to magnesiumcontaining aluminum alloys beyond that achievable by the inclusion ofother alloying elements in the aluminum alloy. An example stresscorrosion cracking-resistant aluminum alloy product comprises aplurality of alloying elements, including: 3 wt. % to 10 wt. % magnesiumor 6 wt. % to 15 wt. % zinc, magnesium, and copper combined, and 0.001wt. % to 0.1 wt. % calcium; and aluminum. In some embodiments, thestress corrosion cracking-resistant aluminum alloy product furthercomprises 0.001 wt. % to 0.1 wt. % strontium. In some embodiments, thestress corrosion cracking-resistant aluminum alloy product furthercomprises 0.001 wt. % to 0.1 wt. % silver. In embodiments, aluminumconstitutes a remainder of the stress corrosion cracking-resistantaluminum alloy product (i.e., a remainder of the alloy beyond thealloying elements and any unavoidable impurities). The aluminum alloymay be in any suitable temper, such as an H temper or a T temper, whichmay be dependent upon the particular aluminum alloy used. Examplealuminum alloys include 5xxx series aluminum alloys and 7xxx seriesaluminum alloys. Optionally, the plurality of alloying elements does notinclude zinc; that is, in some cases, the alloy does not contain zinc oronly contains zinc in trace amounts or as unavoidable impurities.Optionally, the plurality of alloying elements further comprises zinc,such as in an amount of from 0.1 wt. % to 15 wt. %.

The stress corrosion cracking-resistant aluminum alloy productsdescribed herein can be prepared and processed according to any suitablemethods. In embodiments, a stress corrosion cracking-resistant aluminumalloy product is prepared by casting an aluminum alloy comprisingaluminum, 3 wt. % to 10 wt. % magnesium or 6 wt. % to 15 wt. % zinc,magnesium, and copper combined, and 0.001 wt. % to 0.01 wt. % calcium.Optionally, the cast aluminum product is subjected to one or more hotrolling processes and/or one or more cold rolling processes. Otherexample processes may include, but are not limited to, homogenizationprocesses, heat treatment processes, aging processes, or the like.

In embodiments, magnesium containing aluminum alloys may containmagnesium-containing precipitates, which may correspond to intermetallicparticles. Example magnesium-containing precipitates include, Mg₅Al₈beta phase particles and MgZn₂ eta phase particles. The presence of thedifferent magnesium-containing precipitates may depend upon theparticular alloy and processing conditions. Magnesium-containingprecipitates may, in some cases, serve as corrosion initiation sites andallow for corrosion to propagate and for stress corrosion cracking to beproblematic. By including calcium in the aluminum alloys, the presenceor concentrations of magnesium-containing precipitates may be limited orreduced and/or the corrosion potential of the magnesium-containingprecipitates may be reduced. In some embodiments, a stress corrosioncracking-resistant aluminum alloy product comprises less than 0.05 wt. %of magnesium-containing precipitates, such as Mg₅Al₈ beta phaseparticles or MgZn₂ eta phase particles. In some cases,magnesium-containing precipitates may also comprise Zn.

As noted above, the presence of magnesium-containing precipitates may bedictated by the specific composition of an aluminum alloy as well as theprocessing conditions by which the aluminum alloy is made. In someembodiments, magnesium-containing precipitates in a stress corrosioncracking-resistant aluminum alloy product may be formed through exposureto a temperature of from 50° C. to 600° C. Optionally, themagnesium-containing precipitates are formed during aging of an aluminumalloy product.

By including calcium, strontium, and/or silver in the alloy, calcium,strontium, and/or silver may be present in magnesium-containingprecipitates and/or may modify the composition of themagnesium-containing precipitates as compared to alloys where calcium,strontium, and/or silver may only be present in trace amounts. Inclusionof calcium, strontium, and/or silver in a magnesium-containingprecipitate may lower the corrosion potential of themagnesium-containing precipitate as compared to magnesium-containingprecipitates that do not include calcium, strontium, and/or silver.Optionally, a presence of the calcium, strontium, and/or silver in thealuminum alloy product reduces an amount of the magnesium-containingprecipitates in the stress corrosion cracking-resistant aluminum alloyproduct as referenced to a comparable aluminum alloy product comprising3 wt. % to 10 wt. % magnesium or 6 wt. % to 15 wt. % zinc, magnesium,and copper combined, and less than 0.001 wt. % calcium, strontium,and/or silver and subjected to identical processing conditions.

When calcium, strontium, and/or silver are present in an aluminum alloy,precipitates containing calcium, strontium, and/or silver may develop atgrain boundaries. Optionally, a stress corrosion cracking-resistantaluminum alloy product may comprise one or more phases containingcalcium, strontium, and/or silver at grain boundaries of the aluminumalloy product. In some cases, the one or more phases containing calcium,strontium, and/or silver may be produced by exposure to an elevatedtemperature of from 50° C. to 600° C. and/or by aging. Optionally, theone or more phases containing calcium, strontium, and/or silvercomprises calcium metal, strontium metal, and/or silver metal.Optionally, one phase of the one or more phases containing calcium,strontium, and/or silver comprises calcium and magnesium. Optionally,one phase of the one or more phases containing calcium, strontium,and/or silver comprises strontium and magnesium. Optionally, one phaseof the one or more phases containing calcium, strontium, and/or silvercomprises silver and magnesium. Optionally, one phase of the one or morephases containing calcium, strontium, and/or silver comprises calciumand aluminum. Optionally, one phase of the one or more phases containingcalcium, strontium, and/or silver comprises strontium and aluminum.Optionally, one phase of the one or more phases containing calcium,strontium, and/or silver comprises silver and aluminum. Optionally, onephase of the one or more phases containing calcium, strontium, and/orsilver comprises calcium, aluminum, and magnesium. Optionally, one phaseof the one or more phases containing calcium, strontium, and/or silvercomprises strontium, aluminum, and magnesium. Optionally, one phase ofthe one or more phases containing calcium, strontium, and/or silvercomprises calcium, strontium, aluminum, and magnesium. Optionally, onephase of the one or more phases containing calcium, strontium, and/orsilver comprises calcium, silver, aluminum, and magnesium. Optionally,one phase of the one or more phases containing calcium, strontium,and/or silver comprises strontium, silver, aluminum, and magnesium.Optionally, one phase of the one or more phases containing calcium,strontium, and/or silver comprises calcium, strontium, silver, aluminum,and magnesium. In some cases, the one or more phases containing calcium,strontium, and/or silver may at least partially surroundmagnesium-containing precipitates located at the grain boundaries, whichmay optionally limit or reduce the corrosion potential of themagnesium-containing precipitates.

In another aspect, methods of making stress corrosion cracking-resistantaluminum alloy products are described. An example method of this aspectcomprises providing an aluminum alloy in a molten state as a moltenaluminum alloy, such as an aluminum alloy that comprises aluminum, 3 wt.% to 10 wt. % magnesium or 6 wt. % to 15 wt. % zinc, magnesium, andcopper combined, and 0.001 wt. % to 0.1 wt. % calcium; and casting themolten aluminum alloy to form an aluminum alloy product. Otherprocessing techniques may also be employed in the methods of thisaspect. For example, methods of this aspect may optionally comprise oneor more of homogenizing the aluminum alloy product to form a homogenizedaluminum alloy product; aging the aluminum alloy product; cold rollingthe aluminum alloy product; hot rolling the aluminum alloy product;subjecting the aluminum alloy product to an elevated temperature; orsubjecting the aluminum alloy product to a corrosive environment.Advantageously, the stress corrosion cracking-resistant aluminum alloysdescribed herein may be useful in marine environments or other highcorrosion or corrosion susceptible environments.

Advantageously a presence of calcium, strontium, and/or silver in thealuminum alloy product may increase an amount of time needed to inducestress corrosion cracks in the aluminum alloy product as referenced to acomparable aluminum alloy product comprising 3 wt. % to 10 wt. %magnesium or 6 wt. % to 15 wt. % zinc, magnesium, and copper combined,and less than 0.001 wt. % calcium, strontium, and/or silver.

Other objects and advantages will be apparent from the followingdetailed description of non-limiting examples.

BRIEF DESCRIPTION OF THE FIGURES

The specification makes reference to the following appended figures, inwhich use of like reference numerals in different figures is intended toillustrate like or analogous components.

FIG. 1A schematically illustrates the formation of magnesium-containingprecipitates at grain boundaries.

FIG. 1B schematically illustrates corrosion occurring nearmagnesium-containing precipitates particles at grain boundaries.

FIG. 2 provides an overview of an exemplary method of making an aluminumalloy product.

DETAILED DESCRIPTION

Described herein are aluminum alloy products and systems and methods ofmaking and using aluminum alloy products. The aluminum alloy productsdescribed herein include those comprising magnesium-strengthenedaluminum alloys with added calcium, strontium, and/or silver.Advantageously, the added calcium, strontium, and/or silver reduce thealuminum alloy's susceptibility to stress corrosion cracking. By addingcalcium, strontium, and/or silver, the growth of magnesium-containingprecipitates, such as Mg₅Al₈ beta phase particles or MgZn₂ eta phaseparticles at the grain boundaries may optionally be altered and/orreduced as compared to aluminum alloys containing no or only traceamounts of calcium, strontium, and/or silver. The altered and/or reducedgrowth of beta or eta phase particles can reduce or limit corrosion thatmay occur between the beta phase and the surrounding grains, therebysuppressing stress corrosion cracking.

Definitions and Descriptions

As used herein, the terms “invention,” “the invention,” “this invention”and “the present invention” are intended to refer broadly to all of thesubject matter of this patent application and the claims below.Statements containing these terms should be understood not to limit thesubject matter described herein or to limit the meaning or scope of thepatent claims below.

In this description, reference is made to alloys identified by AAnumbers and other related designations, such as “series” or “7xxx.” Foran understanding of the number designation system most commonly used innaming and identifying aluminum and its alloys, see “International AlloyDesignations and Chemical Composition Limits for Wrought Aluminum andWrought Aluminum Alloys” or “Registration Record of Aluminum AssociationAlloy Designations and Chemical Compositions Limits for Aluminum Alloysin the Form of Castings and Ingot,” both published by The AluminumAssociation.

As used herein, a plate generally has a thickness of greater than about15 mm. For example, a plate may refer to an aluminum product having athickness of greater than about 15 mm, greater than about 20 mm, greaterthan about 25 mm, greater than about 30 mm, greater than about 35 mm,greater than about 40 mm, greater than about 45 mm, greater than about50 mm, or greater than about 100 mm.

As used herein, a shate (also referred to as a sheet plate) generallyhas a thickness of from about 4 mm to about 15 mm. For example, a shatemay have a thickness of about 4 mm, about 5 mm, about 6 mm, about 7 mm,about 8 mm, about 9 mm, about 10 mm, about 11 mm, about 12 mm, about 13mm, about 14 mm, or about 15 mm.

As used herein, a sheet generally refers to an aluminum product having athickness of less than about 4 mm. For example, a sheet may have athickness of less than about 4 mm, less than about 3 mm, less than about2 mm, less than about 1 mm, less than about 0.5 mm, or less than about0.3 mm (e.g., about 0.2 mm).

Reference may be made in this application to alloy temper or condition.For an understanding of the alloy temper descriptions most commonlyused, see “American National Standards (ANSI) H35 on Alloy and TemperDesignation Systems.” An F condition or temper refers to an aluminumalloy as fabricated. An O condition or temper refers to an aluminumalloy after annealing. An Hxx condition or temper, also referred toherein as an H temper, refers to a non-heat treatable aluminum alloyafter cold rolling with or without thermal treatment (e.g., annealing).Suitable H tempers include HX1, HX2, HX3 HX4, HX5, HX6, HX7, HX8, or HX9tempers. A T1 condition or temper refers to an aluminum alloy cooledfrom hot working and naturally aged (e.g., at room temperature). A T2condition or temper refers to an aluminum alloy cooled from hot working,cold worked and naturally aged. A T3 condition or temper refers to analuminum alloy solution heat treated, cold worked, and naturally aged. AT4 condition or temper refers to an aluminum alloy solution heat treatedand naturally aged. A T5 condition or temper refers to an aluminum alloycooled from hot working and artificially aged (at elevatedtemperatures). A T6 condition or temper refers to an aluminum alloysolution heat treated and artificially aged. A T7 condition or temperrefers to an aluminum alloy solution heat treated and artificiallyoveraged. A T8x condition or temper refers to an aluminum alloy solutionheat treated, cold worked, and artificially aged. A T9 condition ortemper refers to an aluminum alloy solution heat treated, artificiallyaged, and cold worked. A W condition or temper refers to an aluminumalloy after solution heat treatment.

As used herein, terms such as “cast metal product,” “cast product,”“cast aluminum alloy product,” and the like are interchangeable andrefer to a product produced by direct chill casting (including directchill co-casting) or semi-continuous casting, continuous casting(including, for example, by use of a twin belt caster, a twin rollcaster, a block caster, or any other continuous caster), electromagneticcasting, hot top casting, or any other casting method.

As used herein, the meaning of “room temperature” can include atemperature of from about 15° C. to about 30° C., for example about 15°C., about 16° C., about 17° C., about 18° C., about 19° C., about 20°C., about 21° C., about 22° C., about 23° C., about 24° C., about 25°C., about 26° C., about 27° C., about 28° C., about 29° C., or about 30°C. As used herein, the meaning of “ambient conditions” can includetemperatures of about room temperature, relative humidity of from about20% to about 100%, and barometric pressure of from about 975 millibar(mbar) to about 1050 mbar. For example, relative humidity can be about20%, about 21%, about 22%, about 23%, about 24%, about 25%, about 26%,about 27%, about 28%, about 29%, about 30%, about 31%, about 32%, about33%, about 34%, about 35%, about 36%, about 37%, about 38%, about 39%,about 40%, about 41%, about 42%, about 43%, about 44%, about 45%, about46%, about 47%, about 48%, about 49%, about 50%, about 51%, about 52%,about 53%, about 54%, about 55%, about 56%, about 57%, about 58%, about59%, about 60%, about 61%, about 62%, about 63%, about 64%, about 65%,about 66%, about 67%, about 68%, about 69%, about 70%, about 71%, about72%, about 73%, about 74%, about 75%, about 76%, about 77%, about 78%,about 79%, about 80%, about 81%, about 82%, about 83%, about 84%, about85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%,about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about98%, about 99%, about 100%, or anywhere in between. For example,barometric pressure can be about 975 mbar, about 980 mbar, about 985mbar, about 990 mbar, about 995 mbar, about 1000 mbar, about 1005 mbar,about 1010 mbar, about 1015 mbar, about 1020 mbar, about 1025 mbar,about 1030 mbar, about 1035 mbar, about 1040 mbar, about 1045 mbar,about 1050 mbar, or anywhere in between.

All ranges disclosed herein are to be understood to encompass any andall subranges subsumed therein. For example, a stated range of “1 to 10”should be considered to include any and all subranges between (andinclusive of) the minimum value of 1 and the maximum value of 10; thatis, all subranges beginning with a minimum value of 1 or more, e.g. 1 to6.1, and ending with a maximum value of 10 or less, e.g., 5.5 to 10.Unless stated otherwise, the expression “up to” when referring to thecompositional amount of an element means that element is optional andincludes a zero percent composition of that particular element. Unlessstated otherwise, all compositional percentages are in weight percent(wt. %).

As used herein, the meaning of “a,” “an,” and “the” includes singularand plural references unless the context clearly dictates otherwise.

In the following examples, the aluminum alloy products and theircomponents are described in terms of their elemental composition inweight percent (wt. %). In each alloy, the remainder is aluminum, with amaximum wt. % of 0.15% for the sum of all impurities.

Incidental elements, such as grain refiners and deoxidizers, or otheradditives may be present in aspects of the invention and may add othercharacteristics on their own without departing from or significantlyaltering the alloy described herein or the characteristics of the alloydescribed herein.

Unavoidable impurities, including materials or elements, may be presentin the alloy in minor amounts due to inherent properties of aluminum orleaching from contact with processing equipment. Some impurities foundin aluminum may include iron and silicon. The alloy, as described, maycontain no more than about 0.25 wt. % of any element besides thealloying elements, incidental elements, and unavoidable impurities.

Described herein are methods of treating and preparing metals and metalalloys, including aluminum, aluminum alloys, magnesium, magnesiumalloys, magnesium composites, and steel, among others, and the resultanttreated and prepared metals and metal alloys. In some examples, themetals for use in the methods described herein include aluminum alloys,for example, 5xxx series aluminum alloys or 7xxx series aluminum alloys.In some examples, the materials for use in the methods described hereininclude non-ferrous materials, including aluminum, aluminum alloys,magnesium, magnesium-based materials, magnesium alloys, magnesiumcomposites, titanium, titanium-based materials, titanium alloys, copper,copper-based materials, composites, sheets used in composites, or anyother suitable metal, non-metal or combination of materials. Monolithicas well as non-monolithic, such as roll-bonded materials, claddedalloys, cladding layers, composite materials, such as but not limited tocarbon fiber-containing materials, or various other materials are alsouseful with the methods described herein. In some examples, aluminumalloys containing iron are useful with the methods described herein.

Non-limiting exemplary 5xxx series aluminum alloys for use as thealuminum alloy product can include AA5005, AA5005A, AA5205, AA5305,AA5505, AA5605, AA5006, AA5106, AA5010, AA5110, AA5110A, AA5210, AA5310,AA5016, AA5017, AA5018, AA5018A, AA5019, AA5019A, AA5119, AA5119A,AA5021, AA5022, AA5023, AA5024, AA5026, AA5027, AA5028, AA5040, AA5140,AA5041, AA5042, AA5043, AA5049, AA5149, AA5249, AA5349, AA5449, AA5449A,AA5050, AA5050A, AA5050C, AA5150, AA5051, AA5051A, AA5151, AA5251,AA5251A, AA5351, AA5451, AA5052, AA5252, AA5352, AA5154, AA5154A,AA5154B, AA5154C, AA5254, AA5354, AA5454, AA5554, AA5654, AA5654A,AA5754, AA5854, AA5954, AA5056, AA5356, AA5356A, AA5456, AA5456A,AA5456B, AA5556, AA5556A, AA5556B, AA5556C, AA5257, AA5457, AA5557,AA5657, AA5058, AA5059, AA5070, AA5180, AA5180A, AA5082, AA5182, AA5083,AA5183, AA5183A, AA5283, AA5283A, AA5283B, AA5383, AA5483, AA5086,AA5186, AA5087, AA5187, or AA5088.

Non-limiting exemplary 7xxx series aluminum alloys for use in themethods described herein can include AA7011, AA7019, AA7020, AA7021,AA7039, AA7072, AA7075, AA7085, AA7108, AA7108A, AA7015, AA7017, AA7018,AA7019A, AA7024, AA7025, AA7028, AA7030, AA7031, AA7033, AA7035,AA7035A, AA7046, AA7046A, AA7003, AA7004, AA7005, AA7009, AA7010,AA7011, AA7012, AA7014, AA7016, AA7116, AA7122, AA7023, AA7026, AA7029,AA7129, AA7229, AA7032, AA7033, AA7034, AA7036, AA7136, AA7037, AA7040,AA7140, AA7041, AA7049, AA7049A, AA7149, 7204, AA7249, AA7349, AA7449,AA7050, AA7050A, AA7150, AA7250, AA7055, AA7155, AA7255, AA7056, AA7060,AA7064, AA7065, AA7068, AA7168, AA7175, AA7475, AA7076, AA7178, AA7278,AA7278A, AA7081, AA7181, AA7185, AA7090, AA7093, AA7095, or AA7099.

The following description will serve to further illustrate the presentinvention without, at the same time, however, constituting anylimitation thereof. On the contrary, it is to be clearly understood thatresort may be had to various embodiments, modifications, and equivalentsthereof which, after reading the description herein, may suggestthemselves to those skilled in the art without departing from the spiritof the invention.

High-strength and durable aluminum alloys are desirable for use in anumber of different applications. Magnesium in solid solution iseffective in strengthening the aluminum alloys, and the alloys are alsorelatively inert because magnesium oxide that forms at the surfacecreates a barrier to corrosion. However, aluminum alloys having amagnesium, such as a relatively high content magnesium in the case ofcertain 5xxx aluminum alloys or a relatively high combined content ofzinc, magnesium, and copper in the case of certain 7xxx aluminum alloys,may, nonetheless, experience stress corrosion cracking.

Stress corrosion cracking of aluminum alloys containing magnesiuminvolves a condition where magnesium-containing particles precipitate atthe edge of a recrystallized grain at increased temperature and/or overtime, which promotes the nucleation and growth of Mg₅Al₈ beta phaseparticles or MgZn₂ eta phase particles at the recrystallized grainboundary. FIG. 1A schematically illustrates a grain structure of amagnesium-containing aluminum alloy and shows the presence of the Mg₅Al₈beta phase particles 105 at the grain boundaries 110. The relativeelectronegativity of the Mg₅Al₈ beta phase with respect to thesurrounding material in the grain may generate a corrosion event nearthe Mg₅Al₈ beta phase particles. Eventually, the corrosion cells,coupled with the Mg₅Al₈ beta phase, may form weak areas 115 in themicrostructure, as schematically illustrated in the grain structuredepicted in FIG. 1B, which may crack or tear under stress. Similarcorrosion behavior may be observed in aluminum alloys with discontinuousprecipitation of MgZn₂ eta phase along grain boundaries. Although Mg₅Al₈and MgZn₂ are described as exemplary magnesium-containing precipitatesor magnesium-containing intermetallic compounds that may form particlesat the grain boundaries, other magnesium-containing phases or compounds,such as Mg₅Al₃ or others, may also be formed at the grain boundaries ofthe magnesium-strengthened aluminum alloy and/or may make the alloysusceptible to stress corrosion cracking.

In the case of 5xxx aluminum alloys, precipitation of magnesium at grainboundaries, such as formation of Mg₅Al₈ beta phase particles at grainboundaries, may be more prominent when the magnesium content is 3 wt. %or higher, and the Mg₅Al₈ beta phase may optionally form asemi-continuous string of particles along some grain boundaries.However, depending on the processing and/or operating conditions,magnesium precipitation, such as Mg₅Al₈ beta phase formation, may alsooccur when the magnesium content is below 3 wt. %. Depending on themagnesium content, the magnesium-containing precipitates may or may notbe continuous, or may be separated or scattered. However, cracks maynonetheless propagate and compromise strength, and may eventually causefailure of the alloy product.

In the case of 7xxx aluminum alloys, precipitation of magnesium at grainboundaries, such as formation of MgZn₂ eta phase particles at grainboundaries, may be more prominent when a combined content of magnesiumzinc, magnesium, and copper is 6 wt. % or higher, and the MgZn₂ etaphase may optionally form a semi-continuous string of particles alongsome grain boundaries. However, depending on the processing and/oroperating conditions, magnesium precipitation, such as MgZn₂ eta phaseformation, may also occur when the combined content of zinc, magnesium,and copper is below 6 wt. %. Depending on the magnesium content, themagnesium-containing precipitates may or may not be continuous, or maybe separated or scattered. However, cracks may nonetheless propagate andcompromise strength, and may eventually cause failure of the alloyproduct.

Increased or elevated temperatures may lead to the growth of themagnesium-containing precipitates, such as temperatures from 50° C. to600° C. In some embodiments, the elevated temperature that may lead tothe growth of the magnesium-containing precipitates, such as Mg₅Al₈ orMgZn₂ may not be very high, and may be below 200° C., such as below 150°C., below 100° C., below 50° C., or even lower. Therefore, heattreatment, if performed for magnesium-strengthened aluminum alloys, maybe limited or require close control so as to limit the formation of themagnesium-containing precipitates. However, increases in temperature maynot be avoided and/or may occur during subsequent handling of productsmade of various magnesium-strengthened aluminum alloys, such as duringwelding, paint baking, etc. Therefore, the magnesium-containingprecipitates may inevitably form and create preferential corrosion siteswhich may eventually lead to stress corrosion cracking.

To suppress stress corrosion cracking, calcium, strontium and/or silvermay be added to magnesium-strengthened aluminum alloys to reducecorrosion that may otherwise occur at the grain boundaries due to thepresence of the magnesium-containing precipitates when no calcium,strontium, and/or silver are added. By adding calcium, strontium, and/orsilver, the growth of the magnesium-containing precipitates may bealtered. Without intending to be bound to any particular theory, theinventors believe that, given a relatively low solubility in aluminum,calcium or strontium, or optionally silver, may precipitate, along withmagnesium, at the grain boundaries when the magnesium-strengthenedaluminum alloy is subjected to an elevated temperature. The magnesiumprecipitate, the calcium precipitate, the strontium precipitate, and/orthe silver precipitate may form one or more intermetallic compounds thatmay or may not include aluminum. The formation of intermetalliccompounds containing magnesium, calcium, strontium, and/or silver mayreduce the amount of magnesium that may otherwise formmagnesium-containing precipitates, such as Mg₅Al₈ and/or MgZn₂. Theoverall reduction in the magnesium-containing precipitates may lead toreduced corrosion at the grain boundaries, thereby suppressing orreducing the stress corrosion cracking phenomenon, such as when comparedto magnesium-containing aluminum alloys that lack or only contain traceamounts of calcium, strontium, and/or silver. A trace amount of each ofcalcium, strontium, and/or silver may refer to an amount of each ofcalcium, strontium, and/or silver that may be less than 0.001 wt. %.Alternatively, the precipitates or particles containing calcium,strontium, and/or silver may coat and/or be positioned adjacent to themagnesium-containing precipitates that may be formed at the grainboundaries, thereby limiting the corrosion reaction between themagnesium-containing precipitates and the surrounding grains. Theductility of the oxide film at the crack tip may also be modifiedconstructively by adding calcium and/or strontium. Additionally, calciumand/or strontium can vary or positively form a very stable pacifyinglayer in the region of the crack tip, reducing the overall growth rateof an initiated crack in a denuded region of the grain. Further, thecalcium, strontium, and/or silver remaining in the grains may alter theelectronegativity of the grains themselves and/or a relativeelectronegativity of the grains as compared to the magnesium-containingprecipitates, and thus limit the corrosion that may occur where themagnesium-containing precipitates may be present.

Depending on the application, the amount of calcium that may be added tothe magnesium-strengthened aluminum alloy may range from 0.001% to 0.1%by weight. In some embodiments, the weight percent of calcium in thealloy may be from 0.001% to 0.1%, from 0.005% to 0.1%, from 0.01% to0.1%, from 0.015% to 0.1%, from 0.02% to 0.1%, from 0.025% to 0.1%, from0.03% to 0.1%, from 0.035% to 0.1%, from 0.04% to 0.1%, from 0.045% to0.1%, from 0.05% to 0.1%, from 0.055% to 0.1%, from 0.06% to 0.1%, from0.065% to 0.1%, from 0.07% to 0.1%, from 0.075% to 0.1%, from 0.08% to0.1%, from 0.085% to 0.1%, from 0.09% to 0.1%, from 0.095% to 0.1%, from0.001% to 0.095%, from 0.005% to 0.095%, from 0.01% to 0.095%, from0.015% to 0.095%, from 0.02% to 0.095%, from 0.025% to 0.095%, from0.03% to 0.095%, from 0.035% to 0.095%, from 0.04% to 0.095%, from0.045% to 0.095%, from 0.05% to 0.095%, from 0.055% to 0.095%, from0.06% to 0.095%, from 0.065% to 0.095%, from 0.07% to 0.095%, from0.075% to 0.095%, from 0.08% to 0.095%, from 0.085% to 0.095%, from0.09% to 0.095%, from 0.001% to 0.09%, from 0.005% to 0.09%, from 0.01%to 0.09%, from 0.015% to 0.09%, from 0.02% to 0.09%, from 0.025% to0.09%, from 0.03% to 0.09%, from 0.035% to 0.09%, from 0.04% to 0.09%,from 0.045% to 0.09%, from 0.05% to 0.09%, from 0.055% to 0.09%, from0.06% to 0.09%, from 0.065% to 0.09%, from 0.07% to 0.09%, from 0.075%to 0.09%, from 0.08% to 0.09%, from 0.085% to 0.09%, from 0.001% to0.085%, from 0.005% to 0.085%, from 0.01% to 0.085%, from 0.015% to0.085%, from 0.02% to 0.085%, from 0.025% to 0.085%, from 0.03% to0.085%, from 0.035% to 0.085%, from 0.04% to 0.085%, from 0.045% to0.085%, from 0.05% to 0.085%, from 0.055% to 0.085%, from 0.06% to0.085%, from 0.065% to 0.085%, from 0.07% to 0.085%, from 0.075% to0.085%, from 0.08% to 0.085%, from 0.001% to 0.08%, from 0.005% to0.08%, from 0.01% to 0.08%, from 0.015% to 0.08%, from 0.02% to 0.08%,from 0.025% to 0.08%, from 0.03% to 0.08%, from 0.035% to 0.08%, from0.04% to 0.08%, from 0.045% to 0.08%, from 0.05% to 0.08%, from 0.055%to 0.08%, from 0.06% to 0.08%, from 0.065% to 0.08%, from 0.07% to0.08%, from 0.075% to 0.08%, from 0.001% to 0.075%, from 0.005% to0.075%, from 0.01% to 0.075%, from 0.015% to 0.075%, from 0.02% to0.075%, from 0.025% to 0.075%, from 0.03% to 0.075%, from 0.035% to0.075%, from 0.04% to 0.075%, from 0.045% to 0.075%, from 0.05% to0.075%, from 0.055% to 0.075%, from 0.06% to 0.075%, from 0.065% to0.075%, from 0.07% to 0.075%, from 0.001% to 0.07%, from 0.005% to0.07%, from 0.01% to 0.07%, from 0.015% to 0.07%, from 0.02% to 0.07%,from 0.025% to 0.07%, from 0.03% to 0.07%, from 0.035% to 0.07%, from0.04% to 0.07%, from 0.045% to 0.07%, from 0.05% to 0.07%, from 0.055%to 0.07%, from 0.06% to 0.07%, from 0.065% to 0.07, from 0.001% to0.065%, from 0.005% to 0.065%, from 0.01% to 0.065%, from 0.015% to0.065%, from 0.02% to 0.065%, from 0.025% to 0.065%, from 0.03% to0.065%, from 0.035% to 0.065%, from 0.04% to 0.065%, from 0.045% to0.065%, from 0.05% to 0.065%, from 0.055% to 0.065%, from 0.06% to0.065%, from 0.001% to 0.06%, from 0.005% to 0.06%, from 0.01% to 0.06%,from 0.015% to 0.06%, from 0.02% to 0.06%, from 0.025% to 0.06%, from0.03% to 0.06%, from 0.035% to 0.06%, from 0.04% to 0.06%, from 0.045%to 0.06%, from 0.05% to 0.06%, from 0.055% to 0.06%, from 0.001% to0.055%, from 0.005% to 0.055%, from 0.01% to 0.055%, from 0.015% to0.055%, from 0.02% to 0.055%, from 0.025% to 0.055%, from 0.03% to0.055%, from 0.035% to 0.055%, from 0.04% to 0.055%, from 0.045% to0.055%, from 0.05% to 0.055%, from 0.001% to 0.05%, from 0.005% to0.05%, from 0.01% to 0.05%, from 0.015% to 0.05%, from 0.02% to 0.05%,from 0.025% to 0.05%, from 0.03% to 0.05%, from 0.035% to 0.05%, from0.04% to 0.05%, from 0.045% to 0.05%, from 0.001% to 0.045%, from 0.005%to 0.045%, from 0.01% to 0.045%, from 0.015% to 0.045%, from 0.02% to0.045%, from 0.025% to 0.045%, from 0.03% to 0.045%, from 0.035% to0.045%, from 0.04% to 0.045%, from 0.001% to 0.04%, from 0.005% to0.04%, from 0.01% to 0.04%, from 0.015% to 0.04%, from 0.02% to 0.04%,from 0.025% to 0.04%, from 0.03% to 0.04%, from 0.035% to 0.04%, from0.001% to 0.035%, from 0.005% to 0.035%, from 0.01% to 0.035%, from0.015% to 0.035%, from 0.02% to 0.035%, from 0.025% to 0.035%, from0.03% to 0.035%, from 0.001% to 0.03%, from 0.005% to 0.03%, from 0.01%to 0.03%, from 0.015% to 0.03%, from 0.02% to 0.03%, from 0.025% to0.03%, from 0.001% to 0.025%, from 0.005% to 0.025%, from 0.01% to0.025%, from 0.015% to 0.025%, from 0.02% to 0.025%, from 0.001% to0.02%, from 0.005% to 0.02%, from 0.01% to 0.02%, from 0.015% to 0.02%,from 0.001% to 0.015%, from 0.005% to 0.015%, from 0.01% to 0.015%, from0.001% to 0.01%, from 0.005% to 0.01%, or from 0.001% to 0.005%.

Depending on the application, the amount of strontium that may be addedto the magnesium-strengthened aluminum alloy may range from 0.001% to0.1% by weight. In some embodiments, the weight percent of strontium inthe alloy may be from 0.001% to 0.1%, from 0.005% to 0.1%, from 0.01% to0.1%, from 0.015% to 0.1%, from 0.02% to 0.1%, from 0.025% to 0.1%, from0.03% to 0.1%, from 0.035% to 0.1%, from 0.04% to 0.1%, from 0.045% to0.1%, from 0.05% to 0.1%, from 0.055% to 0.1%, from 0.06% to 0.1%, from0.065% to 0.1%, from 0.07% to 0.1%, from 0.075% to 0.1%, from 0.08% to0.1%, from 0.085% to 0.1%, from 0.09% to 0.1%, from 0.095% to 0.1%, from0.001% to 0.095%, from 0.005% to 0.095%, from 0.01% to 0.095%, from0.015% to 0.095%, from 0.02% to 0.095%, from 0.025% to 0.095%, from0.03% to 0.095%, from 0.035% to 0.095%, from 0.04% to 0.095%, from0.045% to 0.095%, from 0.05% to 0.095%, from 0.055% to 0.095%, from0.06% to 0.095%, from 0.065% to 0.095%, from 0.07% to 0.095%, from0.075% to 0.095%, from 0.08% to 0.095%, from 0.085% to 0.095%, from0.09% to 0.095%, from 0.001% to 0.09%, from 0.005% to 0.09%, from 0.01%to 0.09%, from 0.015% to 0.09%, from 0.02% to 0.09%, from 0.025% to0.09%, from 0.03% to 0.09%, from 0.035% to 0.09%, from 0.04% to 0.09%,from 0.045% to 0.09%, from 0.05% to 0.09%, from 0.055% to 0.09%, from0.06% to 0.09%, from 0.065% to 0.09%, from 0.07% to 0.09%, from 0.075%to 0.09%, from 0.08% to 0.09%, from 0.085% to 0.09%, from 0.001% to0.085%, from 0.005% to 0.085%, from 0.01% to 0.085%, from 0.015% to0.085%, from 0.02% to 0.085%, from 0.025% to 0.085%, from 0.03% to0.085%, from 0.035% to 0.085%, from 0.04% to 0.085%, from 0.045% to0.085%, from 0.05% to 0.085%, from 0.055% to 0.085%, from 0.06% to0.085%, from 0.065% to 0.085%, from 0.07% to 0.085%, from 0.075% to0.085%, from 0.08% to 0.085%, from 0.001% to 0.08%, from 0.005% to0.08%, from 0.01% to 0.08%, from 0.015% to 0.08%, from 0.02% to 0.08%,from 0.025% to 0.08%, from 0.03% to 0.08%, from 0.035% to 0.08%, from0.04% to 0.08%, from 0.045% to 0.08%, from 0.05% to 0.08%, from 0.055%to 0.08%, from 0.06% to 0.08%, from 0.065% to 0.08%, from 0.07% to0.08%, from 0.075% to 0.08%, from 0.001% to 0.075%, from 0.005% to0.075%, from 0.01% to 0.075%, from 0.015% to 0.075%, from 0.02% to0.075%, from 0.025% to 0.075%, from 0.03% to 0.075%, from 0.035% to0.075%, from 0.04% to 0.075%, from 0.045% to 0.075%, from 0.05% to0.075%, from 0.055% to 0.075%, from 0.06% to 0.075%, from 0.065% to0.075%, from 0.07% to 0.075%, from 0.001% to 0.07%, from 0.005% to0.07%, from 0.01% to 0.07%, from 0.015% to 0.07%, from 0.02% to 0.07%,from 0.025% to 0.07%, from 0.03% to 0.07%, from 0.035% to 0.07%, from0.04% to 0.07%, from 0.045% to 0.07%, from 0.05% to 0.07%, from 0.055%to 0.07%, from 0.06% to 0.07%, from 0.065% to 0.07, from 0.001% to0.065%, from 0.005% to 0.065%, from 0.01% to 0.065%, from 0.015% to0.065%, from 0.02% to 0.065%, from 0.025% to 0.065%, from 0.03% to0.065%, from 0.035% to 0.065%, from 0.04% to 0.065%, from 0.045% to0.065%, from 0.05% to 0.065%, from 0.055% to 0.065%, from 0.06% to0.065%, from 0.001% to 0.06%, from 0.005% to 0.06%, from 0.01% to 0.06%,from 0.015% to 0.06%, from 0.02% to 0.06%, from 0.025% to 0.06%, from0.03% to 0.06%, from 0.035% to 0.06%, from 0.04% to 0.06%, from 0.045%to 0.06%, from 0.05% to 0.06%, from 0.055% to 0.06%, from 0.001% to0.055%, from 0.005% to 0.055%, from 0.01% to 0.055%, from 0.015% to0.055%, from 0.02% to 0.055%, from 0.025% to 0.055%, from 0.03% to0.055%, from 0.035% to 0.055%, from 0.04% to 0.055%, from 0.045% to0.055%, from 0.05% to 0.055%, from 0.001% to 0.05%, from 0.005% to0.05%, from 0.01% to 0.05%, from 0.015% to 0.05%, from 0.02% to 0.05%,from 0.025% to 0.05%, from 0.03% to 0.05%, from 0.035% to 0.05%, from0.04% to 0.05%, from 0.045% to 0.05%, from 0.001% to 0.045%, from 0.005%to 0.045%, from 0.01% to 0.045%, from 0.015% to 0.045%, from 0.02% to0.045%, from 0.025% to 0.045%, from 0.03% to 0.045%, from 0.035% to0.045%, from 0.04% to 0.045%, from 0.001% to 0.04%, from 0.005% to0.04%, from 0.01% to 0.04%, from 0.015% to 0.04%, from 0.02% to 0.04%,from 0.025% to 0.04%, from 0.03% to 0.04%, from 0.035% to 0.04%, from0.001% to 0.035%, from 0.005% to 0.035%, from 0.01% to 0.035%, from0.015% to 0.035%, from 0.02% to 0.035%, from 0.025% to 0.035%, from0.03% to 0.035%, from 0.001% to 0.03%, from 0.005% to 0.03%, from 0.01%to 0.03%, from 0.015% to 0.03%, from 0.02% to 0.03%, from 0.025% to0.03%, from 0.001% to 0.025%, from 0.005% to 0.025%, from 0.01% to0.025%, from 0.015% to 0.025%, from 0.02% to 0.025%, from 0.001% to0.02%, from 0.005% to 0.02%, from 0.01% to 0.02%, from 0.015% to 0.02%,from 0.001% to 0.015%, from 0.005% to 0.015%, from 0.01% to 0.015%, from0.001% to 0.01%, from 0.005% to 0.01%, or from 0.001% to 0.005%.

Depending on the application, the amount of silver that may be added tothe magnesium-strengthened aluminum alloy may range from 0.001% to 0.1%by weight. In some embodiments, the weight percent of silver in thealloy may be from 0.001% to 0.1%, from 0.005% to 0.1%, from 0.01% to0.1%, from 0.015% to 0.1%, from 0.02% to 0.1%, from 0.025% to 0.1%, from0.03% to 0.1%, from 0.035% to 0.1%, from 0.04% to 0.1%, from 0.045% to0.1%, from 0.05% to 0.1%, from 0.055% to 0.1%, from 0.06% to 0.1%, from0.065% to 0.1%, from 0.07% to 0.1%, from 0.075% to 0.1%, from 0.08% to0.1%, from 0.085% to 0.1%, from 0.09% to 0.1%, from 0.095% to 0.1%, from0.001% to 0.095%, from 0.005% to 0.095%, from 0.01% to 0.095%, from0.015% to 0.095%, from 0.02% to 0.095%, from 0.025% to 0.095%, from0.03% to 0.095%, from 0.035% to 0.095%, from 0.04% to 0.095%, from0.045% to 0.095%, from 0.05% to 0.095%, from 0.055% to 0.095%, from0.06% to 0.095%, from 0.065% to 0.095%, from 0.07% to 0.095%, from0.075% to 0.095%, from 0.08% to 0.095%, from 0.085% to 0.095%, from0.09% to 0.095%, from 0.001% to 0.09%, from 0.005% to 0.09%, from 0.01%to 0.09%, from 0.015% to 0.09%, from 0.02% to 0.09%, from 0.025% to0.09%, from 0.03% to 0.09%, from 0.035% to 0.09%, from 0.04% to 0.09%,from 0.045% to 0.09%, from 0.05% to 0.09%, from 0.055% to 0.09%, from0.06% to 0.09%, from 0.065% to 0.09%, from 0.07% to 0.09%, from 0.075%to 0.09%, from 0.08% to 0.09%, from 0.085% to 0.09%, from 0.001% to0.085%, from 0.005% to 0.085%, from 0.01% to 0.085%, from 0.015% to0.085%, from 0.02% to 0.085%, from 0.025% to 0.085%, from 0.03% to0.085%, from 0.035% to 0.085%, from 0.04% to 0.085%, from 0.045% to0.085%, from 0.05% to 0.085%, from 0.055% to 0.085%, from 0.06% to0.085%, from 0.065% to 0.085%, from 0.07% to 0.085%, from 0.075% to0.085%, from 0.08% to 0.085%, from 0.001% to 0.08%, from 0.005% to0.08%, from 0.01% to 0.08%, from 0.015% to 0.08%, from 0.02% to 0.08%,from 0.025% to 0.08%, from 0.03% to 0.08%, from 0.035% to 0.08%, from0.04% to 0.08%, from 0.045% to 0.08%, from 0.05% to 0.08%, from 0.055%to 0.08%, from 0.06% to 0.08%, from 0.065% to 0.08%, from 0.07% to0.08%, from 0.075% to 0.08%, from 0.001% to 0.075%, from 0.005% to0.075%, from 0.01% to 0.075%, from 0.015% to 0.075%, from 0.02% to0.075%, from 0.025% to 0.075%, from 0.03% to 0.075%, from 0.035% to0.075%, from 0.04% to 0.075%, from 0.045% to 0.075%, from 0.05% to0.075%, from 0.055% to 0.075%, from 0.06% to 0.075%, from 0.065% to0.075%, from 0.07% to 0.075%, from 0.001% to 0.07%, from 0.005% to0.07%, from 0.01% to 0.07%, from 0.015% to 0.07%, from 0.02% to 0.07%,from 0.025% to 0.07%, from 0.03% to 0.07%, from 0.035% to 0.07%, from0.04% to 0.07%, from 0.045% to 0.07%, from 0.05% to 0.07%, from 0.055%to 0.07%, from 0.06% to 0.07%, from 0.065% to 0.07, from 0.001% to0.065%, from 0.005% to 0.065%, from 0.01% to 0.065%, from 0.015% to0.065%, from 0.02% to 0.065%, from 0.025% to 0.065%, from 0.03% to0.065%, from 0.035% to 0.065%, from 0.04% to 0.065%, from 0.045% to0.065%, from 0.05% to 0.065%, from 0.055% to 0.065%, from 0.06% to0.065%, from 0.001% to 0.06%, from 0.005% to 0.06%, from 0.01% to 0.06%,from 0.015% to 0.06%, from 0.02% to 0.06%, from 0.025% to 0.06%, from0.03% to 0.06%, from 0.035% to 0.06%, from 0.04% to 0.06%, from 0.045%to 0.06%, from 0.05% to 0.06%, from 0.055% to 0.06%, from 0.001% to0.055%, from 0.005% to 0.055%, from 0.01% to 0.055%, from 0.015% to0.055%, from 0.02% to 0.055%, from 0.025% to 0.055%, from 0.03% to0.055%, from 0.035% to 0.055%, from 0.04% to 0.055%, from 0.045% to0.055%, from 0.05% to 0.055%, from 0.001% to 0.05%, from 0.005% to0.05%, from 0.01% to 0.05%, from 0.015% to 0.05%, from 0.02% to 0.05%,from 0.025% to 0.05%, from 0.03% to 0.05%, from 0.035% to 0.05%, from0.04% to 0.05%, from 0.045% to 0.05%, from 0.001% to 0.045%, from 0.005%to 0.045%, from 0.01% to 0.045%, from 0.015% to 0.045%, from 0.02% to0.045%, from 0.025% to 0.045%, from 0.03% to 0.045%, from 0.035% to0.045%, from 0.04% to 0.045%, from 0.001% to 0.04%, from 0.005% to0.04%, from 0.01% to 0.04%, from 0.015% to 0.04%, from 0.02% to 0.04%,from 0.025% to 0.04%, from 0.03% to 0.04%, from 0.035% to 0.04%, from0.001% to 0.035%, from 0.005% to 0.035%, from 0.01% to 0.035%, from0.015% to 0.035%, from 0.02% to 0.035%, from 0.025% to 0.035%, from0.03% to 0.035%, from 0.001% to 0.03%, from 0.005% to 0.03%, from 0.01%to 0.03%, from 0.015% to 0.03%, from 0.02% to 0.03%, from 0.025% to0.03%, from 0.001% to 0.025%, from 0.005% to 0.025%, from 0.01% to0.025%, from 0.015% to 0.025%, from 0.02% to 0.025%, from 0.001% to0.02%, from 0.005% to 0.02%, from 0.01% to 0.02%, from 0.015% to 0.02%,from 0.001% to 0.015%, from 0.005% to 0.015%, from 0.01% to 0.015%, from0.001% to 0.01%, from 0.005% to 0.01%, or from 0.001% to 0.005%.

In the case of a 5xxx aluminum alloy, the amount of magnesium that thealloy may contain may range from 3% to 10% by weight. In someembodiments, the weight percent of magnesium may be from 3% to 10%, from3.5% to 10%, from 4% to 10%, from 4.5% to 10%, from 5% to 10%, from 5.5%to 10%, from 6% to 10%, from 6.5% to 10%, from 7% to 10%, from 7.5% to10%, from 8% to 10%, from 8.5% to 10%, from 9% to 10%, from 9.5% to 10%,from 3% to 9.5%, from 3.5% to 9.5%, from 4% to 9.5%, from 4.5% to 9.5%,from 5% to 9.5%, from 5.5% to 9.5%, from 6% to 9.5%, from 6.5% to 9.5%,from 7% to 9.5%, from 7.5% to 9.5%, from 8% to 9.5%, from 8.5% to 9.5%,from 9% to 9.5%, from 3% to 9%, from 3.5% to 9%, from 4% to 9%, from4.5% to 9%, from 5% to 9%, from 5.5% to 9%, from 6% to 9%, from 6.5% to9%, from 7% to 9%, from 7.5% to 9%, from 8% to 9%, from 8.5% to 9%, from3% to 8.5%, from 3.5% to 8.5%, from 4% to 8.5%, from 4.5% to 8.5%, from5% to 8.5%, from 5.5% to 8.5%, from 6% to 8.5%, from 6.5% to 8.5%, from7% to 8.5%, from 7.5% to 8.5%, from 8% to 8.5%, from 3% to 8%, from 3.5%to 8%, from 4% to 8%, from 4.5% to 8%, from 5% to 8%, from 5.5% to 8%,from 6% to 8%, from 6.5% to 8%, from 7% to 8%, from 7.5% to 8%, from 3%to 7.5%, from 3.5% to 7.5%, from 4% to 7.5%, from 4.5% to 7.5%, from 5%to 7.5%, from 5.5% to 7.5%, from 6% to 7.5%, from 6.5% to 7.5%, from 7%to 7.5%, from 3% to 7%, from 3.5% to 7%, from 4% to 7%, from 4.5% to 7%,from 5% to 7%, from 5.5% to 7%, from 6% to 7%, from 6.5% to 7%, from 3%to 6.5%, from 3.5% to 6.5%, from 4% to 6.5%, from 4.5% to 6.5%, from 5%to 6.5%, from 5.5% to 6.5%, from 6% to 6.5%, from 3% to 6%, from 3.5% to6%, from 4% to 6%, from 4.5% to 6%, from 5% to 6%, from 5.5% to 6%, from3% to 5.5%, from 3.5% to 5.5%, from 4% to 5.5%, from 4.5% to 5.5%, from5% to 5.5%, from 3% to 5%, from 3.5% to 5%, from 4% to 5%, from 4.5% to5%, from 3% to 4.5%, from 3.5% to 4.5%, from 4% to 4.5%, from 3% to 4%,from 3.5% to 4%, or from 3% to 3.5%.

In the case of a 7xxx aluminum alloy, the amount of a combined amount ofzinc, magnesium, and copper that the alloy may contain may range from 6%to 15% by weight. In some embodiments, the combined weight percent ofzinc, magnesium, and copper may be from 6% to 15%, from 6% to 14.5%,from 6% to 14%, from 6% to 13.5%, from 6% to 13%, from 6% to 12.5%, from6% to 12%, from 6% to 11.5%, from 6% to 11%, from 6% to 10.5%, from 6%to 10%, from 6% to 9.5%, from 6% to 9%, from 6% to 8.5%, from 6% to 8%,from 6% to 7.5%, from 6% to 7%, from 6% to 6.5%, from 6.5% to 15%, from6.5% to 14.5%, from 6.5% to 14%, from 6.5% to 13.5%, from 6.5% to 13%,from 6.5% to 12.5%, from 6.5% to 12%, from 6.5% to 11.5%, from 6.5% to11%, from 6.5% to 10.5%, from 6.5% to 10%, from 6.5% to 9.5%, from 6.5%to 9%, from 6.5% to 8.5%, from 6.5% to 8%, from 6.5% to 7.5%, from 6.5%to 7%, from 7% to 15%, from 7% to 14.5%, from 7% to 14%, from 7% to13.5%, from 7% to 13%, from 7% to 12.5%, from 7% to 12%, from 7% to11.5%, from 7% to 11%, from 7% to 10.5%, from 7% to 10%, from 7% to9.5%, from 7% to 9%, from 7% to 8.5%, from 7% to 8%, from 7% to 7.5%,from 7.5% to 15%, from 7.5% to 14.5%, from 7.5% to 14%, from 7.5% to13.5%, from 7.5% to 13%, from 7.5% to 12.5%, from 7.5% to 12%, from 7.5%to 11.5%, from 7.5% to 11%, from 7.5% to 10.5%, from 7.5% to 10%, from7.5% to 9.5%, from 7.5% to 9%, from 7.5% to 8.5%, from 7.5% to 8%, from8% to 15%, from 8% to 14.5%, from 8% to 14%, from 8% to 13.5%, from 8%to 13%, from 8% to 12.5%, from 8% to 12%, from 8% to 11.5%, from 8% to11%, from 8% to 10.5%, from 8% to 10%, from 8% to 9.5%, from 8% to 9%,from 8% to 8.5%, from 8.5% to 15%, from 8.5% to 14.5%, from 8.5% to 14%,from 8.5% to 13.5%, from 8.5% to 13%, from 8.5% to 12.5%, from 8.5% to12%, from 8.5% to 11.5%, from 8.5% to 11%, from 8.5% to 10.5%, from 8.5%to 10%, from 8.5% to 9.5%, from 8.5% to 9%, from 9% to 15%, from 9% to14.5%, from 9% to 14%, from 9% to 13.5%, from 9% to 13%, from 9% to12.5%, from 9% to 12%, from 9% to 11.5%, from 9% to 11%, from 9% to10.5%, from 9% to 10%, from 9% to 9.5%, from 9.5% to 15%, from 9.5% to14.5%, from 9.5% to 14%, from 9.5% to 13.5%, from 9.5% to 13%, from 9.5%to 12.5%, from 9.5% to 12%, from 9.5% to 11.5%, from 9.5% to 11%, from9.5% to 10.5%, from 9.5% to 10%, from 10% to 15%, from 10% to 14.5%,from 10% to 14%, from 10% to 13.5%, from 10% to 13%, from 10% to 12.5%,from 10% to 12%, from 10% to 11.5%, from 10% to 11%, from 10% to 10.5%,from 10.5% to 15%, from 10.5% to 14.5%, from 10.5% to 14%, from 10.5% to13.5%, from 10.5% to 13%, from 10.5% to 12.5%, from 10.5% to 12%, from10.5% to 11.5%, from 10.5% to 11%, from 11% to 15%, from 11% to 14.5%,from 11% to 14%, from 11% to 13.5%, from 11% to 13%, from 11% to 12.5%,from 11% to 12%, from 11% to 11.5%, from 11.5% to 15%, from 11.5% to14.5%, from 11.5% to 14%, from 11.5% to 13.5%, from 11.5% to 13%, from11.5% to 12.5%, from 11.5% to 12%, from 12% to 15%, from 12% to 14.5%,from 12% to 14%, from 12% to 13.5%, from 12% to 13%, from 12% to 12.5%,from 12.5% to 15%, from 12.5% to 14.5%, from 12.5% to 14%, from 12.5% to13.5%, from 12.5% to 13%, from 13% to 15%, from 13% to 14.5%, from 13%to 14%, from 13% to 13.5%, from 13.5% to 15%, from 13.5% to 14.5%, from13.5% to 14%, from 14% to 15%, from 14% to 14.5%, or from 14.5% to 15%.

As discussed above, when the magnesium-strengthened aluminum alloycontains 3 wt. % or more magnesium in the case of a 5xxx aluminum alloyor 6 wt. % or more zinc, magnesium, and copper combined in the case of a7xxx aluminum alloy, the alloy may be more prone to stress corrosioncracking. A magnesium-strengthened aluminum alloy that contains lessthan 3 wt. % magnesium or less than 6 wt. % of zinc, magnesium, andcopper combined may nonetheless also be susceptible to stress corrosioncracking. Accordingly, calcium, strontium, and/or silver may also beadded to magnesium-strengthened aluminum alloys having less than 3 wt. %magnesium or less than 6 wt. % of zinc, magnesium, and copper combinedto suppress stress corrosion cracking, especially when the product maybe exposed to corrosive environments, such as a marine environment. Forexample, the amount of magnesium that the 5xxx aluminum alloy maycontain may range from 0.1% to 3% by weight. In some embodiments, theweight percent of magnesium that the 5xxx alloy may contain may rangefrom 0.1% to 1.5%, from 0.1% to 1.5%, from 0.5% to 1.5%, from 1% to1.5%, from 0.1% to 1%, from 0.5% to 1%, or from 1.5% to 3%. Optionally,the amount of magnesium may be from 1.5% to 3%, from 1.6% to 3%, from1.7% to 3%, from 1.8% to 3%, from 1.9% to 3%, from 2% to 3%, from 2.1%to 3%, from 2.2% to 3%, from 2.3% to 3%, from 2.4% to 3%, from 2.5% to3%, from 2.6% to 3%, from 2.7% to 3%, from 2.8% to 3%, from 2.9% to 3%,from 1.5% to 2.9%, from 1.6% to 2.9%, from 1.7% to 2.9%, from 1.8% to2.9%, from 1.9% to 2.9%, from 2% to 2.9%, from 2.1% to 2.9%, from 2.2%to 2.9%, from 2.3% to 2.9%, from 2.4% to 2.9%, from 2.5% to 2.9%, from2.6% to 2.9%, from 2.7% to 2.9%, from 2.8% to 2.9%, from 1.5% to 2.8%,from 1.6% to 2.8%, from 1.7% to 2.8%, from 1.8% to 2.8%, from 1.9% to2.8%, from 2% to 2.8%, from 2.1% to 2.8%, from 2.2% to 2.8%, from 2.3%to 2.8%, from 2.4% to 2.8%, from 2.5% to 2.8%, from 2.6% to 2.8%, from2.7% to 2.8%, from 1.5% to 2.7%, from 1.6% to 2.7%, from 1.7% to 2.7%,from 1.8% to 2.7%, from 1.9% to 2.7%, from 2% to 2.7%, from 2.1% to2.7%, from 2.2% to 2.7%, from 2.3% to 2.7%, from 2.4% to 2.7%, from 2.5%to 2.7%, from 2.6% to 2.7%, from 1.5% to 2.6%, from 1.6% to 2.6%, from1.7% to 2.6%, from 1.8% to 2.6%, from 1.9% to 2.6%, from 2% to 2.6%,from 2.1% to 2.6%, from 2.2% to 2.6%, from 2.3% to 2.6%, from 2.4% to2.6%, from 2.5% to 2.6%, from 1.5% to 2.5%, from 1.6% to 2.5%, from 1.7%to 2.5%, from 1.8% to 2.5%, from 1.9% to 2.5%, from 2% to 2.5%, from2.1% to 2.5%, from 2.2% to 2.5%, from 2.3% to 2.5%, from 2.4% to 2.5%,from 1.5% to 2.4%, from 1.6% to 2.4%, from 1.7% to 2.4%, from 1.8% to2.4%, from 1.9% to 2.4%, from 2% to 2.4%, from 2.1% to 2.4%, from 2.2%to 2.4%, from 2.3% to 2.4%, from 1.5% to 2.3%, from 1.6% to 2.3%, from1.7% to 2.3%, from 1.8% to 2.3%, from 1.9% to 2.3%, from 2% to 2.3%,from 2.1% to 2.3%, from 2.2% to 2.3%, from 1.5% to 2.2%, from 1.6% to2.2%, from 1.7% to 2.2%, from 1.8% to 2.2%, from 1.9% to 2.2%, from 2%to 2.2%, from 2.1% to 2.2%, from 1.5% to 2.1%, from 1.6% to 2.1%, from1.7% to 2.1%, from 1.8% to 2.1%, from 1.9% to 2.1%, from 2% to 2.1%,from 1.5% to 2%, from 1.6% to 2%, from 1.7% to 2%, from 1.8% to 2%, from1.9% to 2%, from 1.5% to 1.9%, from 1.6% to 1.9%, from 1.7% to 1.9%,from 1.8% to 1.9%, from 1.5% to 1.8%, from 1.6% to 1.8%, from 1.7% to1.8%, from 1.5% to 1.7%, from 1.6% to 1.7%, or from 1.5% to 1.6%. Forexample, the combined amount of zinc, magnesium, and copper that the7xxx aluminum alloy may contain may range from 0.5% to 6% by weight. Insome embodiments, the combined weight percent of zinc, magnesium, andcopper that the 7xxx aluminum alloy may contain may range from 0.5% to6%, from 0.5% to 5.5%, from 0.5% to 5%, from 0.5% to 4.5%, from 0.5% to4%, from 0.5% to 3.5%, from 0.5% to 3%, from 0.5% to 2.5%, from 0.5% to2%, from 0.5% to 1.5%, from 0.5% to 1%, from 1% to 6%, from 1% to 5.5%,from 1% to 5%, from 1% to 4.5%, from 1% to 4%, from 1% to 3.5%, from 1%to 3%, from 1% to 2.5%, from 1% to 2%, from 1% to 1.5%, from 1.5% to 6%,from 1.5% to 5.5%, from 1.5% to 5%, from 1.5% to 4.5%, from 1.5% to 4%,from 1.5% to 3.5%, from 1.5% to 3%, from 1.5% to 2.5%, from 1.5% to 2%,from 2% to 6%, from 2% to 5.5%, from 2% to 5%, from 2% to 4.5%, from 2%to 4%, from 2% to 3.5%, from 2% to 3%, from 2% to 2.5%, from 2.5% to 6%,from 2.5% to 5.5%, from 2.5% to 5%, from 2.5% to 4.5%, from 2.5% to 4%,from 2.5% to 3.5%, from 2.5% to 3%, from 3% to 6%, from 3% to 5.5%, from3% to 5%, from 3% to 4.5%, from 3% to 4%, from 3% to 3.5%, from 3.5% to6%, from 3.5% to 5.5%, from 3.5% to 5%, from 3.5% to 4.5%, from 3.5% to4%, from 4% to 6%, from 4% to 5.5%, from 4% to 5%, from 4% to 4.5%, from4.5% to 6%, from 4.5% to 5.5%, from 4.5% to 5%, from 5% to 6%, from 5%to 5.5%, or from 5.5% to 6%.

Depending on the amount of magnesium in the 5xxx aluminum alloy or thecombined amount of zinc, magnesium, and copper in the 7xxx aluminumalloy, the amount of calcium that may be added to effectively suppressstress corrosion cracking may vary. For example, a ratio of the amountof calcium to the amount of magnesium in the 5xxx alloy may range fromabout 0.0001 to about 1. Optionally a ratio of the amount of calcium inthe alloy to the amount of magnesium in the alloy may range from 0.0001to 1, from 0.0001 to 0.1, from 0.0001 to 0.01, from 0.0001 to 0.001,from 0.001 to 1, from 0.001 to 0.1, from 0.001 to 0.01, from 0.01 to 1,from 0.01 to 0.1, or from 0.1 to 1. A ratio of the amount of calcium tothe combined amount of zinc, magnesium, and copper in the 7xxx alloy mayrange from about 0.0001 to about 1. Optionally a ratio of the amount ofcalcium in the alloy to the combined amount of zinc, magnesium, andcopper in the alloy may range from 0.0001 to 1, from 0.0001 to 0.1, from0.0001 to 0.01, from 0.0001 to 0.001, from 0.001 to 1, from 0.001 to0.1, from 0.001 to 0.01, from 0.01 to 1, from 0.01 to 0.1, or from 0.1to 1.

Depending on the amount of magnesium in the 5xxx aluminum alloy or thecombined amount of zinc, magnesium, and copper in the 7xxx aluminumalloy, the amount of strontium that may be added to effectively suppressstress corrosion cracking may vary. For example, a ratio of the amountof strontium to the amount of magnesium in the 5xxx alloy may range fromabout 0.0001 to about 1. Optionally a ratio of the amount of strontiumin the alloy to the amount of magnesium in the alloy may range from0.0001 to 1, from 0.0001 to 0.1, from 0.0001 to 0.01, from 0.0001 to0.001, from 0.001 to 1, from 0.001 to 0.1, from 0.001 to 0.01, from 0.01to 1, from 0.01 to 0.1, or from 0.1 to 1. A ratio of the amount ofstrontium to the combined amount of zinc, magnesium, and copper in the7xxx alloy may range from about 0.0001 to about 1. Optionally a ratio ofthe amount of strontium in the alloy to the combined amount of zinc,magnesium, and copper in the alloy may range from 0.0001 to 1, from0.0001 to 0.1, from 0.0001 to 0.01, from 0.0001 to 0.001, from 0.001 to1, from 0.001 to 0.1, from 0.001 to 0.01, from 0.01 to 1, from 0.01 to0.1, or from 0.1 to 1.

Depending on the amount of magnesium in the 5xxx aluminum alloy or thecombined amount of zinc, magnesium, and copper in the 7xxx aluminumalloy, the amount of silver that may be added to effectively suppressstress corrosion cracking may vary. For example, a ratio of the amountof silver to the amount of magnesium in the 5xxx alloy may range fromabout 0.0001 to about 1. Optionally a ratio of the amount of silver inthe alloy to the amount of magnesium in the alloy may range from 0.0001to 1, from 0.0001 to 0.1, from 0.0001 to 0.01, from 0.0001 to 0.001,from 0.001 to 1, from 0.001 to 0.1, from 0.001 to 0.01, from 0.01 to 1,from 0.01 to 0.1, or from 0.1 to 1. A ratio of the amount of silver tothe combined amount of zinc, magnesium, and copper in the 7xxx alloy mayrange from about 0.0001 to about 1. Optionally a ratio of the amount ofsilver in the alloy to the combined amount of zinc, magnesium, andcopper in the alloy may range from 0.0001 to 1, from 0.0001 to 0.1, from0.0001 to 0.01, from 0.0001 to 0.001, from 0.001 to 1, from 0.001 to0.1, from 0.001 to 0.01, from 0.01 to 1, from 0.01 to 0.1, or from 0.1to 1.

In some embodiments, the amount of zinc that the alloy may contain mayrange from 0.01% to 15% by weight. In some embodiments, the amount ofzinc that the alloy may contain may range from 0.01% to 8% by weight.For example, the weight percent of zinc may be from 0.01% to 8%, 0.05%to 8%, from 0.1% to 8%, from 0.5% to 8%, from 1% to 8%, from 1.5% to 8%,from 2% to 8%, from 2.5% to 8%, from 3% to 8%, from 3.5% to 8%, from 4%to 8%, from 4.5% to 8%, from 5% to 8%, from 5.5% to 8%, from 6% to 8%,from 6.5% to 8%, from 7% to 8%, from 7.5% to 8%, from 0.01% to 7.5%,0.05% to 7.5%, from 0.1% to 7.5%, from 0.5% to 7.5%, from 1% to 7.5%,from 1.5% to 7.5%, from 2% to 7.5%, from 2.5% to 7.5%, from 3% to 7.5%,from 3.5% to 7.5%, from 4% to 7.5%, from 4.5% to 7.5%, from 5% to 7.5%,from 5.5% to 7.5%, from 6% to 7.5%, from 6.5% to 7.5%, from 7% to 7.5%,from 0.01% to 7%, 0.05% to 7%, from 0.1% to 7%, from 0.5% to 7%, from 1%to 7%, from 1.5% to 7%, from 2% to 7%, from 2.5% to 7%, from 3% to 7%,from 3.5% to 7%, from 4% to 7%, from 4.5% to 7%, from 5% to 7%, from5.5% to 7%, from 6% to 7%, from 6.5% to 7%, from 0.01% to 6.5%, 0.05% to6.5%, from 0.1% to 6.5%, from 0.5% to 6.5%, from 1% to 6.5%, from 1.5%to 6.5%, from 2% to 6.5%, from 2.5% to 6.5%, from 3% to 6.5%, from 3.5%to 6.5%, from 4% to 6.5%, from 4.5% to 6.5%, from 5% to 6.5%, from 5.5%to 6.5%, from 6% to 6.5%, from 0.01% to 6%, 0.05% to 6%, from 0.1% to6%, from 0.5% to 6%, from 1% to 6%, from 1.5% to 6%, from 2% to 6%, from2.5% to 6%, from 3% to 6%, from 3.5% to 6%, from 4% to 6%, from 4.5% to6%, from 5% to 6%, from 5.5% to 6%, from 0.01% to 5.5%, 0.05% to 5.5%,from 0.1% to 5.5%, from 0.5% to 5.5%, from 1% to 5.5%, from 1.5% to5.5%, from 2% to 5.5%, from 2.5% to 5.5%, from 3% to 5.5%, from 3.5% to5.5%, from 4% to 5.5%, from 4.5% to 5.5%, from 5% to 5.5%, from 0.01% to5%, 0.05% to 5%, from 0.1% to 5%, from 0.5% to 5%, from 1% to 5%, from1.5% to 5%, from 2% to 5%, from 2.5% to 5%, from 3% to 5%, from 3.5% to5%, from 4% to 5%, from 4.5% to 5%, from 0.01% to 4.5%, 0.05% to 4.5%,from 0.1% to 4.5%, from 0.5% to 4.5%, from 1% to 4.5%, from 1.5% to4.5%, from 2% to 4.5%, from 2.5% to 4.5%, from 3% to 4.5%, from 3.5% to4.5%, from 4% to 4.5%, from 0.01% to 4%, 0.05% to 4%, from 0.1% to 4%,from 0.5% to 4%, from 1% to 4%, from 1.5% to 4%, from 2% to 4%, from2.5% to 4%, from 3% to 4%, from 3.5% to 4%, from 0.01% to 3.5%, 0.05% to3.5%, from 0.1% to 3.5%, from 0.5% to 3.5%, from 1% to 3.5%, from 1.5%to 3.5%, from 2% to 3.5%, from 2.5% to 3.5%, from 3% to 3.5%, from 0.01%to 3%, 0.05% to 3%, from 0.1% to 3%, from 0.5% to 3%, from 1% to 3%,from 1.5% to 3%, from 2% to 3%, from 2.5% to 3%, from 0.01% to 2.5%,0.05% to 2.5%, from 0.1% to 2.5%, from 0.5% to 2.5%, from 1% to 2.5%,from 1.5% to 2.5%, from 2% to 2.5%, from 0.01% to 2%, 0.05% to 2%, from0.1% to 2%, from 0.5% to 2%, from 1% to 2%, from 1.5% to 2%, from 0.01%to 1.5%, 0.05% to 1.5%, from 0.1% to 1.5%, from 0.5% to 1.5%, from 1% to1.5%, from 0.01% to 1%, 0.05% to 1%, from 0.1% to 1%, from 0.5% to 1%,from 0.01% to 0.5%, 0.05% to 0.5%, from 0.1% to 0.5%, from 0.01% to0.1%, 0.05% to 0.1%, or from 0.01% to 0.05%.

In some embodiments, the amount of zinc that the alloy may contain mayrange from 8% to 15% by weight. For example, the weight percent of zincmay be from 8% to 15%, from 8.5% to 15%, from 9% to 15%, from 9.5% to15%, from 10% to 15%, from 10.5% to 15%, from 11% to 15%, from 11.5% to15%, from 12% to 15%, from 12.5% to 15%, from 13% to 15%, from 13.5% to15%, from 14% to 15%, from 14.5% to 15%, from 8% to 14.5%, from 8.5% to14.5%, from 9% to 14.5%, from 9.5% to 14.5%, from 10% to 14.5%, from10.5% to 14.5%, from 11% to 14.5%, from 11.5% to 14.5%, from 12% to14.5%, from 12.5% to 14.5%, from 13% to 14.5%, from 13.5% to 14.5%, from14% to 14.5%, from 8% to 14%, from 8.5% to 14%, from 9% to 14%, from9.5% to 14%, from 10% to 14%, from 10.5% to 14%, from 11% to 14%, from11.5% to 14%, from 12% to 14%, from 12.5% to 14%, from 13% to 14%, from13.5% to 14%, from 8% to 13.5%, from 8.5% to 13.5%, from 9% to 13.5%,from 9.5% to 13.5%, from 10% to 13.5%, from 10.5% to 13.5%, from 11% to13.5%, from 11.5% to 13.5%, from 12% to 13.5%, from 12.5% to 13.5%, from13% to 13.5%, from 8% to 13%, from 8.5% to 13%, from 9% to 13%, from9.5% to 13%, from 10% to 13%, from 10.5% to 13%, from 11% to 13%, from11.5% to 13%, from 12% to 13%, from 12.5% to 13%, from 8% to 12.5%, from8.5% to 12.5%, from 9% to 12.5%, from 9.5% to 12.5%, from 10% to 12.5%,from 10.5% to 12.5%, from 11% to 12.5%, from 11.5% to 12.5%, from 12% to12.5%, from 8% to 12%, from 8.5% to 12%, from 9% to 12%, from 9.5% to12%, from 10% to 12%, from 10.5% to 12%, from 11% to 12%, from 11.5% to12%, from 8% to 11.5%, from 8.5% to 11.5%, from 9% to 11.5%, from 9.5%to 11.5%, from 10% to 11.5%, from 10.5% to 11.5%, from 11% to 11.5%,from 8% to 11%, from 8.5% to 11%, from 9% to 11%, from 9.5% to 11%, from10% to 11%, from 10.5% to 11%, from 8% to 10%, from 8.5% to 10%, from 9%to 10%, from 9.5% to 10%, from 8% to 9.5%, from 8.5% to 9.5%, from 9% to9.5%, from 8% to 9%, from 8.5% to 9%, or from 8% to 8.5%.

In some embodiments, the alloy may not include zinc as an alloyingelement, and only may include zinc as an incidental element orunavoidable impurity.

As mentioned above, the aluminum alloy families that may be moresusceptible to stress corrosion cracking as compared to other aluminumalloys may include the 5xxx series and the 7xxx series.

FIG. 2 provides an overview of an exemplary method of making an aluminumalloy product. The method of FIG. 2 begins at step 205 where moltenaluminum alloy 206 is cast to form a cast aluminum alloy product 207,such as an ingot or other cast product. Although FIG. 2 depicts aschematic illustration of a direct chill casting process, the aluminumalloys described herein can also be cast using a continuous castingprocess. A continuous casting system can include a pair of movingopposed casting surfaces (e.g., moving opposed belts, rolls, or blocks),a casting cavity between the pair of moving opposed casting surfaces,and a molten metal injector. The molten metal injector can have an endopening from which molten metal can exit the molten metal injector andbe injected into the casting cavity.

The molten aluminum alloy 206 may include molten aluminum, magnesium,and calcium and optionally strontium or silver. In some embodiments, themolten aluminum alloy 206 may further include zinc. The amount (byweight percentage) of magnesium, calcium, and zinc, respectively, may beany of the various amounts discussed above or a subrange thereof.Depending on the application, the molten aluminum alloy 206 may furtherinclude one or more other alloying elements, e.g., manganese, zirconium,scandium, silicon, iron, copper, chromium, titanium, etc.

The cast aluminum alloy product 207 may then be processed by anysuitable means. As discussed above, heat treatment for conventionalmagnesium-strengthened aluminum alloys may be avoided or may requireclose control, if performed, so as to limit the formation of themagnesium-containing precipitates, which eventually may lead to stresscorrosion cracking. Accordingly, conventional magnesium-strengthenedaluminum alloys are typically work hardened and are in an H condition ortemper. In contrast, when calcium is added to the magnesium-strengthenedaluminum alloy as disclosed herein, the alloy may be significantly lesssusceptible to stress corrosion cracking as discussed above.Accordingly, the magnesium-strengthened aluminum alloy including calciumas an alloying element may be work hardened and/or heat treated. Theresultant alloy may be in an H temper or T temper, as appropriate.Suitable H tempers may include H1X, H2X, H3X, H4X, or the like, such asH111, H112, H115, H116, H12, H14, H16, H18, H19, H24, H26, H28, H32,H321, H323, H34, H343, H36, H38, etc. Suitable T tempers may include T1,T2, T3, T351, T352, T3510, T3511, T36, T361, T4, T42, T451, T4510,T4511, T5, T6, T62, T651, T6510, T6511, T7, T72, T73, T7351, T8, T81,T851, T8510, T8511, T9, T10, etc. Exemplary processing steps may includehomogenization, hot rolling, cold rolling, annealing, solution heattreatment, pre-aging, or the like.

Some exemplary processing steps are shown in FIG. 2 . At step 210, thecast aluminum alloy product 207 is homogenized to form a homogenizedaluminum alloy product 211. In the homogenization step, the cast product207 described herein may be heated, such as to a temperature rangingfrom about 400° C. to about 500° C. For example, the product 207 can beheated to a temperature of about 400° C., about 410° C., about 420° C.,about 430° C., about 440° C., about 450° C., about 460° C., about 470°C., about 480° C., about 490° C., or about 500° C. The product 207 isthen allowed to soak (i.e., held at the indicated temperature) for aperiod of time. In some examples, the total time for the homogenizationstep, including the heating and soaking phases, can be up to 24 hours.For example, the product 207 can be heated up to 500° C. and soaked, fora total time of up to 18 hours for the homogenization step. Optionally,the product 207 can be heated to below 490° C. and soaked, for a totaltime of greater than 18 hours for the homogenization step. In somecases, the homogenization step comprises multiple processes. In somenon-limiting examples, the homogenization step includes heating theproduct 207 to a first temperature for a first period of time followedby heating to a second temperature for a second period of time. Forexample, the product 207 can be heated to about 465° C. for about 3.5hours and then heated to about 480° C. for about 6 hours.

Following the homogenization step, at step 215, the homogenized aluminumalloy product 211 is subjected to one or more rolling passes to form arolled aluminum alloy product 212, which may correspond to an aluminumalloy article, such as an aluminum alloy plate, an aluminum alloy shate,or an aluminum alloy sheet that is coiled after rolling.

In the case where a hot rolling step is performed, prior to hot rolling,the homogenized product 211 can be allowed to cool to a temperature suchas between 300° C. to 450° C. For example, the homogenized product 211can be allowed to cool to a temperature of between 325° C. to 425° C. orfrom 350° C. to 400° C. In some embodiments, the cast product can be acontinuously cast product that can be allowed to cool to a temperaturebetween 300° C. to 450° C. The product can then be hot rolled at asuitable temperature, such as between 300° C. to 450° C., to form a hotrolled intermediate product such as a hot rolled plate, a hot rolledshate or a hot rolled sheet having a gauge between 3 mm and 200 mm(e.g., 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 15 mm, 20 mm, 25mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75mm, 80 mm, 85 mm, 90 mm, 95 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm,150 mm, 160 mm, 170 mm, 180 mm, 190 mm, 200 mm, or anywhere in between).During hot rolling, temperatures and other operating parameters can becontrolled so that the temperature of the hot rolled intermediateproduct upon exit from the hot rolling mill is no more than 470° C., nomore than 450° C., no more than 440° C., or no more than 430° C.

The hot rolled product can then be cold rolled into a cold rolledproduct having a gauge between about 0.5 to 10 mm, e.g., between about0.7 to 6.5 mm. Optionally, the cold rolled sheet can have a gauge of 0.5mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, 5.0mm, 5.5 mm, 6.0 mm, 6.5 mm, 7.0 mm, 7.5 mm, 8.0 mm, 8.5 mm, 9.0 mm, 9.5mm, or 10.0 mm. The cold rolling can be performed to result in a finalgauge thickness that represents a gauge reduction of up to 85% (e.g., upto 10%, up to 20%, up to 30%, up to 40%, up to 50%, up to 60%, up to70%, up to 80%, or up to 85% reduction) as compared to the hot rolledproduct. In some embodiments, an interannealing step can be performedduring the cold rolling step. The interannealing step can be performedat a temperature of from about 300° C. to about 450° C. (e.g., about310° C., about 320° C., about 330° C., about 340° C., about 350° C.,about 360° C., about 370° C., about 380° C., about 390° C., about 400°C., about 410° C., about 420° C., about 430° C., about 440° C., or about450° C.). In some cases, the interannealing step comprises multipleprocesses. In some non-limiting examples, the interannealing stepincludes heating the cold rolled product to a first temperature for afirst period of time followed by heating to a second temperature for asecond period of time. For example, the cold rolled product can beheated to about 410° C. for about 1 hour and then heated to about 330°C. for about 2 hours.

In some embodiments, a rolled product can undergo a solution heattreatment step. The solution heat treatment step can be any treatmentfor the sheet which results in solutionizing of the soluble particles.Because the magnesium-strengthened aluminum alloy with added calcium maybe less susceptible to stress corrosion cracking, the solution heattreatment may be omitted. In the case where a solution heat treatment isperformed, the rolled product can be heated to a peak metal temperature(PMT) of up to 590° C. (e.g., from 400° C. to 590° C.) and soaked for aperiod of time at the temperature. For example, the rolled product canbe soaked at 480° C. for a soak time of up to 30 minutes (e.g., 0seconds, 60 seconds, 75 seconds, 90 seconds, 5 minutes, 10 minutes, 20minutes, 25 minutes, or 30 minutes). After heating and soaking, theproduct can be rapidly cooled at rates greater than 200° C./s to atemperature between 500 and 200° C. In one example, the product issubjected to a quench rate of above 200° C./second at temperaturesbetween 450° C. and 200° C. Optionally, the cooling rates can be fasterin other cases.

After quenching, the heat treated product can optionally undergo apre-aging treatment by reheating the product before coiling. Thepre-aging treatment can be performed at a temperature of from about 70°C. to about 125° C. for a period of time of up to 6 hours. For example,the pre-aging treatment can be performed at a temperature of about 70°C., about 75° C., about 80° C., about 85° C., about 90° C., about 95°C., about 100° C., about 105° C., about 110° C., about 115° C., about120° C., or about 125° C. In some embodiments, the pre-aging treatmentcan be performed for about 30 minutes, about 1 hour, about 2 hours,about 3 hours, about 4 hours, about 5 hours, or about 6 hours. Thepre-aging treatment can be carried out by passing the plate, shate, orsheet through a heating device, such as a device that emits radiantheat, convective heat, induction heat, infrared heat, or the like.

The cast products described herein can be used to make products in theform of plates or other suitable products. For example, plates includingthe products as described herein can be prepared by processing an ingotin a homogenization step or casting a product in a continuous casterfollowed by a hot rolling step. In the hot rolling step, the castproduct can be hot rolled to a 200 mm thick gauge or less (e.g., fromabout 10 mm to about 200 mm). For example, the cast product can be hotrolled to a plate having a final gauge thickness of about 10 mm to about175 mm, about 15 mm to about 150 mm, about 20 mm to about 125 mm, about25 mm to about 100 mm, about 30 mm to about 75 mm, or about 35 mm toabout 50 mm.

As discussed above, the added calcium may alter or limit the formationof magnesium-containing precipitates at the grain boundaries when themagnesium-strengthened aluminum alloy may be subjected to an elevatedtemperature. Accordingly, in addition to the heat treatment discussedabove, the magnesium-strengthened aluminum alloys described herein maybe further subjected to an elevated temperature, such as during welding,paint baking, etc., without increasing the risk of or susceptibility tostress corrosion cracking. Depending on the process, the elevatedtemperature may range from 50° C. to 600° C. In some embodiments, theelevated temperature may range from 50° C. to 600° C., 100° C. to 600°C., 150° C. to 600° C., 200° C. to 600° C., 250° C. to 600° C., 300° C.to 600° C., 350° C. to 600° C., 400° C. to 600° C., 450° C. to 600° C.,500° C. to 600° C., 550° C. to 600° C., 50° C. to 550° C., 100° C. to550° C., 150° C. to 550° C., 200° C. to 550° C., 250° C. to 550° C.,300° C. to 550° C., 350° C. to 550° C., 400° C. to 550° C., 450° C. to550° C., 500° C. to 550° C., 50° C. to 500° C., 100° C. to 500° C., 150°C. to 500° C., 200° C. to 500° C., 250° C. to 500° C., 300° C. to 500°C., 350° C. to 500° C., 400° C. to 500° C., 450° C. to 500° C., 50° C.to 450° C., 100° C. to 450° C., 150° C. to 450° C., 200° C. to 450° C.,250° C. to 450° C., 300° C. to 450° C., 350° C. to 450° C., 400° C. to450° C., 50° C. to 400° C., 100° C. to 400° C., 150° C. to 400° C., 200°C. to 400° C., 250° C. to 400° C., 300° C. to 400° C., 350° C. to 400°C., 50° C. to 350° C., 100° C. to 350° C., 150° C. to 350° C., 200° C.to 350° C., 250° C. to 350° C., 300° C. to 350° C., 50° C. to 300° C.,100° C. to 300° C., 150° C. to 300° C., 200° C. to 300° C., 250° C. to300° C., 50° C. to 250° C., 100° C. to 250° C., 150° C. to 250° C., 200°C. to 250° C., 50° C. to 200° C., 100° C. to 200° C., 150° C. to 200°C., 50° C. to 150° C., 100° C. to 150° C., or 50° C. to 100° C.

Given the suppressing effect of the added calcium on stress corrosioncracking, the magnesium-strengthened aluminum alloy may be used incorrosive environments, such as in the case of marine applications,automotive reinforcement/chassis applications, or the like, with reducedsusceptibility to stress corrosion cracking.

All patents, publications and abstracts cited herein are incorporatedherein by reference in their entirety. The foregoing description of theembodiments, including illustrated embodiments, has been presented onlyfor the purpose of illustration and description and is not intended tobe exhaustive or limiting to the precise forms disclosed. Numerousmodifications, adaptations, and uses thereof will be apparent to thoseskilled in the art.

Illustrative Aspects

As used below, any reference to a series of aspects is to be understoodas a reference to each of those examples disjunctively (e.g., “Aspects1-4” is to be understood as “Aspects 1, 2, 3, or 4”).

Aspect 1 is a stress corrosion cracking-resistant aluminum alloyproduct, comprising: a plurality of alloying elements, including: 3 wt.% to 10 wt. % magnesium or 6 wt. % to 15 wt. % zinc, magnesium, andcopper combined; 0.001 wt. % to 0.1 wt. % calcium; and aluminum.

Aspect 2 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein the aluminumconstitutes a remainder of the stress corrosion cracking-resistantaluminum alloy product.

Aspect 3 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein the plurality ofalloying elements further include 0.001 wt. % to 0.1 wt. % strontium.

Aspect 4 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein the plurality ofalloying elements further include 0.001 wt. % to 0.1 wt. % silver.

Aspect 5 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect in an H temper.

Aspect 6 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect in a T temper.

Aspect 7 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect produced by subjecting acast aluminum product to one or more hot rolling processes.

Aspect 8 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect produced by subjecting acast aluminum product to one or more cold rolling processes.

Aspect 9 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, comprising a 5xxx seriesaluminum alloy.

Aspect 10 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein the plurality ofalloying elements does not include zinc.

Aspect 11 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, comprising a 7xxx seriesaluminum alloy.

Aspect 12 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein the plurality ofalloying elements further comprises zinc.

Aspect 13 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein the plurality ofalloying elements comprises 0.1 wt. % to 15 wt. % zinc.

Aspect 14 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, comprisingmagnesium-containing precipitates.

Aspect 15 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, comprising magnesiumand/or aluminum.

Aspect 16 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein themagnesium-containing precipitates comprise Mg₅Al₈ beta phase particles,and wherein the stress corrosion cracking-resistant aluminum alloyproduct comprises less than 0.05 wt. % of the Mg₅Al₈ beta phaseparticles.

Aspect 17 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein themagnesium-containing precipitates comprise Mg and/or Zn.

Aspect 18 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein themagnesium-containing precipitates comprise MgZn₂ eta phase particles,and wherein the stress corrosion cracking-resistant aluminum alloyproduct comprises less than 10 wt. % of the MgZn₂ eta phase particles.

Aspect 19 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein themagnesium-containing precipitates comprise MgZn₂ eta phase particles,and wherein the stress corrosion cracking-resistant aluminum alloyproduct comprises less than 5 wt. % of the MgZn₂ eta phase particles.

Aspect 20 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein themagnesium-containing precipitates comprise MgZn₂ eta phase particles,and wherein the stress corrosion cracking-resistant aluminum alloyproduct comprises less than 1 wt. % of the MgZn₂ eta phase particles.

Aspect 21 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein themagnesium-containing precipitates comprise MgZn₂ eta phase particles,and wherein the stress corrosion cracking-resistant aluminum alloyproduct comprises less than 0.1 wt. % of the MgZn₂ eta phase particles.

Aspect 22 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein themagnesium-containing precipitates comprise MgZn₂ eta phase particles,and wherein the stress corrosion cracking-resistant aluminum alloyproduct comprises less than 0.05 wt. % of the MgZn₂ eta phase particles.

Aspect 23 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein themagnesium-containing precipitates are formed through exposure to atemperature of from 50° C. to 600° C.

Aspect 24 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein themagnesium-containing precipitates are formed during aging.

Aspect 25 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein themagnesium-containing precipitates comprise calcium.

Aspect 26 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein a presence of thecalcium in the aluminum alloy product reduces an amount of themagnesium-containing precipitates in the stress corrosioncracking-resistant aluminum alloy product as referenced to a comparablealuminum alloy product comprising 3 wt. % to 10 wt. % magnesium or 6 wt.% to 12 wt. % zinc, magnesium, and copper combined, and less than 0.001wt. % calcium and subjected to identical processing conditions.

Aspect 27 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, comprising one or morephases containing calcium, strontium, and/or silver at grain boundariesof the aluminum alloy product.

Aspect 28 is the stress corrosion cracking-resistant aluminum alloy ofany previous or subsequent aspect, wherein the one or more phases areproduced by exposure to an elevated temperature of from 50° C. to 600°C.

Aspect 29 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein the one or morephases are produced by aging.

Aspect 30 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein the one or morephases comprises calcium metal.

Aspect 31 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein the one or morephases comprises strontium metal.

Aspect 32 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein the one or morephases comprises silver metal.

Aspect 33 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein one phase of theone or more phases comprises calcium and magnesium.

Aspect 34 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein one phase of theone or more phases comprises strontium and magnesium.

Aspect 35 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein one phase of theone or more phases comprises silver and magnesium.

Aspect 36 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein one phase of theone or more phases comprises calcium and aluminum.

Aspect 37 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein one phase of theone or more phases comprises strontium and aluminum.

Aspect 38 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein one phase of theone or more phases comprises silver and aluminum.

Aspect 39 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein one phase of theone or more phases comprises calcium, aluminum, and magnesium.

Aspect 40 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein one phase of theone or more phases comprises strontium, aluminum, and magnesium.

Aspect 41 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein one phase of theone or more phases comprises calcium, strontium, aluminum, andmagnesium.

Aspect 42 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein one phase of theone or more phases comprises calcium, silver, aluminum, and magnesium.

Aspect 43 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein one phase of theone or more phases comprises strontium, silver, aluminum, and magnesium.

Aspect 44 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein one phase of theone or more phases comprises calcium, strontium, silver, aluminum, andmagnesium.

Aspect 45 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous or subsequent aspect, wherein the one or morephases at least partially surround magnesium-containing precipitateslocated at the grain boundaries.

Aspect 46 is a method of making a stress corrosion cracking-resistantaluminum alloy product, comprising: providing an aluminum alloy in amolten state as a molten aluminum alloy, wherein the aluminum alloycomprises: 3 wt. % to 10 wt. % magnesium or 6 wt. % to 12 wt. % zinc,magnesium, and copper combined; 0.001 wt. % to 0.1 wt. % calcium; andaluminum; and casting the molten aluminum alloy to form an aluminumalloy product.

Aspect 47 is the method of any previous or subsequent aspect, furthercomprising homogenizing the aluminum alloy product to form a homogenizedaluminum alloy product.

Aspect 48 is the method of any previous or subsequent aspect, furthercomprising aging the aluminum alloy product.

Aspect 49 is the method of any previous or subsequent aspect, furthercomprising cold rolling the aluminum alloy product.

Aspect 50 is the method of any previous or subsequent aspect, furthercomprising hot rolling the aluminum alloy product.

Aspect 51 is the method of any previous or subsequent aspect, furthercomprising subjecting the aluminum alloy product to an elevatedtemperature.

Aspect 52 is the method of any previous or subsequent aspect, furthercomprising subjecting the aluminum alloy product to a corrosiveenvironment.

Aspect 53 is the method of any previous or subsequent aspect, wherein apresence of the calcium in the aluminum alloy product increases anamount of time needed to induce stress corrosion cracks in the aluminumalloy product as referenced to a comparable aluminum alloy productcomprising 3 wt. % to 10 wt. % magnesium or 6 wt. % to 12 wt. % zinc,magnesium, and copper combined and less than 0.001 wt. % calcium.

Aspect 54 is the method of any previous or subsequent aspect, furthercomprising subjecting the aluminum alloy to a marine environment.

Aspect 55 is the method of any previous, wherein the aluminum alloyproduct is the stress corrosion cracking-resistant aluminum alloyproduct of any previous aspect.

Aspect 56 is the stress corrosion cracking-resistant aluminum alloyproduct of any previous aspect prepared according to the method of anyprevious aspect.

All patents, publications and abstracts cited above are incorporatedherein by reference in their entirety. The foregoing description of theembodiments, including illustrated embodiments, has been presented onlyfor the purpose of illustration and description and is not intended tobe exhaustive or limiting to the precise forms disclosed. Numerousmodifications, adaptations, and uses thereof will be apparent to thoseskilled in the art.

1. A stress corrosion cracking-resistant aluminum alloy product,comprising: a plurality of alloying elements, including: 3 wt. % to 10wt. % magnesium or 6 wt. % to 15 wt. % zinc, magnesium, and coppercombined; 0.001 wt. % to 0.1 wt. % calcium; and aluminum.
 2. The stresscorrosion cracking-resistant aluminum alloy product of claim 1, whereinthe plurality of alloying elements further include 0.001 wt. % to 0.1wt. % strontium.
 3. The stress corrosion cracking-resistant aluminumalloy product of claim 1, wherein the plurality of alloying elementsfurther include 0.001 wt. % to 0.1 wt. % silver.
 4. The stress corrosioncracking-resistant aluminum alloy product of claim 1 in an H temper. 5.The stress corrosion cracking-resistant aluminum alloy product of claim1 in a T temper.
 6. The stress corrosion cracking-resistant aluminumalloy product of claim 1, comprising a 5xxx series aluminum alloy. 7.The stress corrosion cracking-resistant aluminum alloy product of claim1, wherein the plurality of alloying elements does not include zinc. 8.The stress corrosion cracking-resistant aluminum alloy product of claim1, comprising a 7xxx series aluminum alloy.
 9. The stress corrosioncracking-resistant aluminum alloy product of claim 1, wherein theplurality of alloying elements comprises 0.1 wt. % to 15 wt. % zinc. 10.The stress corrosion cracking-resistant aluminum alloy product of claim1, comprising magnesium-containing precipitates.
 11. The stresscorrosion cracking-resistant aluminum alloy product of claim 10,comprising magnesium and/or aluminum.
 12. The stress corrosioncracking-resistant aluminum alloy product of claim 10, wherein themagnesium-containing precipitates comprise Mg₅Al₈ beta phase particles,and wherein the stress corrosion cracking-resistant aluminum alloyproduct comprises less than 0.05 wt. % by weight of the Mg₅Al₈ betaphase particles.
 13. The stress corrosion cracking-resistant aluminumalloy product of claim 10, wherein the magnesium-containing precipitatescomprise Mg and/or Zn.
 14. The stress corrosion cracking-resistantaluminum alloy product of claim 10, wherein the magnesium-containingprecipitates comprise MgZn₂ eta phase particles, and wherein the stresscorrosion cracking-resistant aluminum alloy product comprises less than10 wt. % of the MgZn₂ eta phase particles.
 15. The stress corrosioncracking-resistant aluminum alloy product of claim 10, wherein themagnesium-containing precipitates comprise calcium.
 16. The stresscorrosion cracking-resistant aluminum alloy product of claim 10, whereina presence of the calcium reduces an amount of the magnesium-containingprecipitates in the stress corrosion cracking-resistant aluminum alloyproduct as referenced to a comparable aluminum alloy product comprising3 wt. % to 10 wt. % magnesium or 6 wt. % to 12 wt. % zinc, magnesium,and copper combined, and less than 0.001 wt. % calcium and subjected toidentical processing conditions.
 17. The stress corrosioncracking-resistant aluminum alloy product of claim 1, comprising one ormore phases containing calcium, strontium, and/or silver at grainboundaries of the stress corrosion cracking-resistant aluminum alloyproduct.
 18. The stress corrosion cracking-resistant aluminum alloyproduct of claim 17, wherein the one or more phases comprises calciummetal.
 19. The stress corrosion cracking-resistant aluminum alloyproduct of claim 17, wherein the one or more phases comprises strontiummetal.
 20. The stress corrosion cracking-resistant aluminum alloyproduct of claim 17, wherein the one or more phases comprises silvermetal.
 21. The stress corrosion cracking-resistant aluminum alloyproduct of claim 17, wherein one phase of the one or more phasescomprises a combination of at least two of calcium, magnesium,strontium, silver, or aluminum.
 22. The stress corrosioncracking-resistant aluminum alloy product of claim 17, wherein one phaseof the one or more phases comprises calcium, strontium, silver,aluminum, and magnesium.
 23. The stress corrosion cracking-resistantaluminum alloy product of claim 17, wherein the one or more phases atleast partially surround magnesium-containing precipitates located atthe grain boundaries.
 24. A method of making a stress corrosioncracking-resistant aluminum alloy product, comprising: providing analuminum alloy in a molten state as a molten aluminum alloy, wherein thealuminum alloy comprises: 3 wt. % to 10 wt. % magnesium or 6 wt. % to 12wt. % zinc, magnesium, and copper combined; 0.001 wt. % to 0.1 wt. %calcium; and aluminum; and casting the molten aluminum alloy to form analuminum alloy product.
 25. The method of claim 24, further comprisinghomogenizing the aluminum alloy product to form a homogenized aluminumalloy product.
 26. The method of claim 24, further comprising one ormore of aging the aluminum alloy product, cold rolling the aluminumalloy product, hot rolling the aluminum alloy product, subjecting thealuminum alloy product to an elevated temperature, or subjecting thealuminum alloy product to a corrosive environment.
 27. The method ofclaim 24, wherein a presence of the calcium in the aluminum alloyproduct increases an amount of time needed to induce stress corrosioncracks in the aluminum alloy product as referenced to a comparablealuminum alloy product comprising 3 wt. % to 10 wt. % magnesium or 6 wt.% to 12 wt. % zinc, magnesium, and copper combined and less than 0.001wt. % calcium.
 28. The method of claim 24, further comprising subjectingthe aluminum alloy to a marine environment.
 29. (canceled) 30.(canceled)